{"id":23006,"date":"2024-10-10T06:30:45","date_gmt":"2024-10-10T01:00:45","guid":{"rendered":"https:\/\/samacheerkalvi.guide\/?p=23006"},"modified":"2024-10-11T09:51:51","modified_gmt":"2024-10-11T04:21:51","slug":"samacheer-kalvi-9th-science-guide-chapter-9","status":"publish","type":"post","link":"https:\/\/samacheerkalvi.guide\/samacheer-kalvi-9th-science-guide-chapter-9\/","title":{"rendered":"Samacheer Kalvi 9th Science Guide Chapter 9 Universe"},"content":{"rendered":"

Tamilnadu State Board New Syllabus Samacheer Kalvi 9th Science Guide<\/a> Pdf Chapter 9 Universe Text Book Back Questions and Answers, Notes.<\/p>\n

Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 9 Universe<\/h2>\n

9th Science Guide Universe Text Book Back Questions and Answers<\/h3>\n

I. Choose the correct answer:<\/span><\/p>\n

\"Samacheer<\/p>\n

Question 1.
\nWho proposed the heliocentric model of the universe?
\n(a) Tycho Brahe
\n(b) Nicolaus Copernicus
\n(c) Ptolemy
\n(d) Archimedes
\nAnswer:
\n(b) Nicolaus Copernicus<\/p>\n

Question 2.
\nWhich of the following is not a part of outer solar system?
\n(a) Mercury
\n(b) Saturn
\n(c) Uranus
\n(d) Neptune
\nAnswer:
\n(a) Mercury<\/p>\n

\"Samacheer<\/p>\n

Question 3.
\nCeres is a …………….
\n(a) Meteor
\n(b) Star
\n(e) Planet
\n(d) Asteroid
\nAnswer:
\n(d) Asteroid<\/p>\n

Question 4.
\nThe period of revolution of planet A around the Sun is 8 times that of planet B. How many times is the distance of planet A as great as that of planet B?
\n(a) 4
\n(b) 5
\n(e) 2
\n(d) 3
\nAnswer:
\n(a) 4<\/p>\n

\"Samacheer<\/p>\n

Question 5.
\nThe Big Bang occurred _____ years ago.
\n(a) 13.7 billion
\n(b) 15 million
\n(e) 15 billion
\n(d) 20 million
\nAnswer:
\n(a) 13.7 billion<\/p>\n

II. Fill in the blanks :<\/span><\/p>\n

1. The speed of Sun in km\/s is ………………
\nAnswer:
\n250 km\/s<\/p>\n

2. The rotational period of the Sun near its poles is ………………
\nAnswer:
\n36 days<\/p>\n

\"Samacheer<\/p>\n

3. India\u2019s first satellite is ……………..
\nAnswer:
\nAryabhatta<\/p>\n

4. The third law of Kepler is also known as the Law of ……………….
\nAnswer:
\nHarmonics<\/p>\n

5. The number of planets in our Solar System is …………………
\nAnswer:
\n8<\/p>\n

\"Samacheer<\/p>\n

III. State whether true or false. If false, correct the statement:<\/span><\/p>\n

1. ISS is a proof for international cooperation.
\nAnswer:
\nTrue.<\/p>\n

2. Halley\u2019s comet appears after hearly 67 hours.
\nAnswer:
\nFalse.
\nCorrect statement: Halley’s comet appears after nearly 76 years.<\/p>\n

3. Satellites nearer to the Earth should have lesser orbital velocity.
\nAnswer:
\nFalse.
\nCorrect statement: Satellites nearer to the Earth should have faster orbital velocity.<\/p>\n

\"Samacheer<\/p>\n

4. Mars is called the red planet.
\nAnswer:
\nTrue.<\/p>\n

IV. Answer briefly :<\/span><\/p>\n

Question 1.
\nWhat is the solar system?
\nAnswer:
\nThe Sun and celestial bodies which revolve around it form the solar system. It consists of a large number of bodies such as planets, comets, asteroids, and meteors.<\/p>\n

Question 2.
\nDefine orbital velocity.
\nAnswer:
\nThe horizontal velocity that has to be imparted to a satellite at the determined height so that it makes a circular orbit around the planet is called “orbital velocity”.<\/p>\n

\"Samacheer<\/p>\n

Question 3.
\nDefine time period of a satellite.
\nAnswer:
\nTime taken by the satellite to complete one revolution around the Earth is called the time period.
\nTime period, T = Distance covered\/Orbital velocity
\nT = 2\u03c0r\/v<\/p>\n

Question 4.
\nWhat is the satellite? What are the two types of satellites?
\nAnswer:
\nA body moving in orbit around a planet is called a satellite.
\nThe two types of Satellites are<\/p>\n

    \n
  1. \u00a0Natural satellites,<\/li>\n
  2. \u00a0Man-made satellites.<\/li>\n<\/ol>\n

    \"Samacheer<\/p>\n

    Question 5.
    \nWrite a note on the inner planets.
    \nAnswer:
    \nThe planets are spaced unevenly. The first four planets are relatively close together and close to the Sun. They form the inner solar system. The four planets grouped together in the inner solar system are Mercury, Venus, Earth, and Mars. They are called inner planets. They have a surface of solid rock crust and so are called terrestrial or rocky planets. Their insides, surfaces, and atmospheres are formed in a similar way and form a similar pattern. Our planet, Earth can be taken as a model of the other three planets.<\/p>\n

    Question 6.
    \nWrite about comets.
    \nAnswer:<\/p>\n

      \n
    • Comets are lumps of dust and ice that revolve around the Sim in highly elliptical orbits.<\/li>\n
    • Their period of revolution is very long.<\/li>\n
    • Comet vapourises and forms a head and tail on approaching the sun.<\/li>\n
    • Tail of the biggest comet may be around 160 million km.<\/li>\n
    • There are period comets (e:g) Halley’s comet which appears after every 76 years.<\/li>\n<\/ul>\n

      \"Samacheer<\/p>\n

      Question 7.
      \nState Kepler\u2019s laws.
      \nAnswer:
      \nIn the early 1600s, Johannes Kepler proposed three laws of planetary motion.
      \nFirst Law – The Law of Ellipses
      \nThe path of the planets about the Sun is elliptical in shape, with the center of the Sun being located at one of the foci.<\/p>\n

      Second Law – The Law of Equal Areas
      \nAn imaginary line drawn from the center of the Sun to the center of the planet will sweep out equal areas in equal intervals of time.<\/p>\n

      Third Law – The Law of Harmonies
      \nThe ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their semi-major axis from the Sun.<\/p>\n

      Question 8.
      \nWhat factors have made life on Earth possible?
      \nAnswer:
      \nFactors responsible for life on Earth.<\/p>\n

        \n
      1. Right distance from the Sun.<\/li>\n
      2. Right temperature.<\/li>\n
      3. Presence of water.<\/li>\n
      4. Suitable atmosphere.<\/li>\n
      5. Blanket of ozone.<\/li>\n<\/ol>\n

        \"Samacheer<\/p>\n

        V. Answer in detail:<\/span><\/p>\n

        Question 1.
        \nGive an account of all the planets in the solar system.
        \nAnswer:<\/p>\n

        The planets are spaced unevenly. The first four planets are relatively close together and close to the Sun. They form the inner solar system. Farther from the Sun is the outer solar system, where the planets are much more spread out. Thus the distance between Saturn and Uranus is much greater (about 20 times) than between the Earth and Mars.<\/p>\n

        The four planets grouped together in the inner solar system are Mercury, Venus, Earth, and Mars. They are called inner planets. They have a surface of solid rock crust and so are called terrestrial or rocky planets. Their insides, surfaces, and atmospheres are formed in a similar way and form a similar pattern. Our planet, Earth can be taken as a model of the other three planets.<\/p>\n

        The four large planets Jupiter, Saturn, Uranus and Neptune spread out in the outer solar system that slowly orbits the Sun are called outer planets. They are made of hydrogen, helium and other gases in huge amounts and have very dense atmosphere. They are known as gas giants and are called gaseous planets. The four outer planets Jupiter, Saturn, Uranus and Neptune have rings whereas the four inner planets do not have any rings. The rings are actually tiny pieces of rock covered with ice.<\/p>\n

        \"Samacheer<\/p>\n

        Question 2.
        \nDiscuss the benefits of ISS.
        \nAnswer:<\/p>\n

        1. Water purification efforts :
        \nThe water recovery system (WRS) and the oxygen generation system (OGS) techniques developed by ISS provides advanced water Alteration and purification to water scarcity areas<\/p>\n

        2. Eye-tracking technology :
        \nEye-tracking technology can be used in many laser surgeries which tracks eye’s position very accurately and helps the disabled people with limited movement and speech.<\/p>\n

        3. Robotic arms and Surgeries :
        \nRobotic arms provide significant help to surgeons in removing inoperable tumours and taking biopsies with great accuracies.<\/p>\n

        4. Apart from the above, there are many other applications such as the development of improved vaccines, breast cancer detection and treatment, and so on.<\/p>\n

        Question 3.
        \nWrite a note on orbital velocity.
        \nAnswer:
        \nNowadays many artificial satellites are launched into the Earth\u2019s orbit. The first artificial satellite Sputnik was launched in 1956. India launched its first satellite Aryabhatta on April 19, 1975. Artificial satellites are made to revolve in an orbit at a height of a few hundred kilometres. At this altitude, the friction due to air is negligible. The satellite is carried by rocket to the desired height and released horizontally with a high velocity so that it remains moving in a nearly circular orbit. The horizontal velocity that has to be imparted to a satellite at the determined height so that it makes a circular orbit around the planet is called orbital velocity.<\/p>\n

        The orbital velocity of the satellite depends on its altitude above Earth. The nearer the object to the Earth, the faster is the required orbital velocity. At an altitude of 200 kilometres, the required orbital velocity is a little more than 27,400 kph. That orbital speed and distance permit the satellite to make one revolution in 24 hours. Since Earth also rotates once in 24 hours, a satellite stays in a fixed position relative to a point on Earth\u2019s surface. Because the satellite stays over the same spot all the time, this kind of orbit is called \u2018geostationary\u2019.<\/p>\n

        Orbital velocity can be calculated using the following formula.
        \nv = \\(\\sqrt{\\frac{\\mathrm{GM}}{(\\mathrm{R}+\\mathrm{h})}}\\)
        \nwhere; G = Gravitational constant (6.673 \u00d7 10– 11<\/sup>Nm2<\/sup>kg– 2<\/sup>)
        \nM = Mass of the Earth (5.972 \u00d7 1024<\/sup>kg)
        \nR = Radius of the Earth (6371 km)
        \nh = Height of the satellite from the surface of the Earth.<\/p>\n

        \"Samacheer<\/p>\n

        VI. Conceptual Questions<\/span><\/p>\n

        Question 1.
        \nWhy do some stars appear blue and some red?
        \nAnswer:<\/p>\n

          \n
        1. Stars appear in different colours depending on their temperatures.<\/li>\n
        2. Hot stars are white or blue in colour.<\/li>\n
        3. Cooler stars are orange or red in colour.<\/li>\n<\/ol>\n

          Question 2.
          \nHow is a satellite maintained in nearly circular orbit?
          \nAnswer:
          \nArtificial satellites are made to revolve in an orbit at a height of a few hundred kilometres. At this altitude, the friction due to air is negligible. The satellite is carried by rocket to the desired height and released horizontally with a high velocity so that it remains moving in a nearly circular orbit.<\/p>\n

          \"Samacheer<\/p>\n

          Question 3.
          \nWhy are some satellites called geostationary?
          \nAnswer:
          \nThe Earth rotates once in 24 hours, a satellite stays in a fixed position.
          \nBecause the satellite stays over the same spot all the time, this kind of orbit is called . “geostationary”.<\/p>\n

          Question 4.
          \nA man weighing 60 kg on the Earth will weigh 1680 kg in the Sun. Why?
          \nAnswer:
          \nMass of the man = 60Kg
          \nw = m \u00d7 g
          \nm = 60Kg, g = 274.13m\/s2<\/sup>
          \nThe sun\u2019s gravitational acceleration is 30 times more than that of the earth. So the person would weigh 16,447N on the surface of the sun.<\/p>\n

          \"Samacheer<\/p>\n

          VII. Numerical Problems<\/span><\/p>\n

          Question 1.
          \nCalculate the speed with which a satellite moves if it is at a height of 36,000 km from the Earth\u2019s surface and has an orbital period of 24 hr (Take R = 6370 km).
          \n[Hint: Convert hr into seconds before doing the calculation)<\/p>\n

          Solution:
          \nGiven:
          \nHeight of the satellite, h = 36,000 km = (36,000) \u00d7103<\/sup>m
          \nRadius of the Earth, R = 6370 km = (6370) \u00d7 103<\/sup>m
          \nWe know: Gravitational constant, G = 6.673 10-11<\/sup>Nm2<\/sup>kg-2<\/sup>
          \nMass of the Earth, M = 5.972 \u00d7 1024<\/sup>kg.
          \n\"Samacheer
          \nOrbital velocity, v = 3.067\u00d710 3<\/sup> m\/s (or) 3067m\/s (or) 3.067 km\/s.<\/p>\n

          Question 2.
          \nAt an orbital height of 400 km, find the orbital period of the satellite.
          \nSolution : Given : Orbital height, h = 400 km = 400 \u00d7 103<\/sup>m
          \nWe know : Gravitational constant, G = 6.673 \u00d7 10-11<\/sup>Nm2<\/sup>kg-2<\/sup>
          \nMass of the earth, M =5.972 \u00d71024<\/sup>kg
          \nRadius of the Earth, R = 6371 km = 6371 \u00d7 10-3<\/sup>m.
          \n\"Samacheer
          \nIntext Activities<\/span><\/p>\n

          ACTIVITY – 1<\/span><\/p>\n

          Form a team of three to four students. Prepare a poster about the astronomers<\/p>\n

          \"Samacheer<\/p>\n

          \"Samacheer<\/p>\n

          ACTIVITY – 2<\/span><\/p>\n

          Observe the sky keenly during night. Can you see group of stars? Can you figure out any shape? Discuss with your teachers and find out their name.
          \nAim : To observe the group of stars in the night sky.<\/p>\n

          Procedure :<\/p>\n

            \n
          1. Observe the night sky keenly.<\/li>\n
          2. Observe the movements of stars<\/li>\n
          3. Imagine the shapes<\/li>\n<\/ol>\n

            Observation :
            \nBy discussing with the teachers following groups are identified.<\/p>\n\n\n\n\n\n\n\n\n\n
            Group of Star<\/td>\nshape<\/td>\n<\/tr>\n
            1. Orion<\/td>\nHunter<\/td>\n<\/tr>\n
            2. pisces<\/td>\nFish<\/td>\n<\/tr>\n
            3. Gemini<\/td>\nTwins table<\/td>\n<\/tr>\n
            4. Leo<\/td>\nLion<\/td>\n<\/tr>\n
            5. Cancer<\/td>\nCrab<\/td>\n<\/tr>\n
            6. Capricornus<\/td>\nSea goat<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

            \"Samacheer<\/p>\n

            ACTIVITY – 3<\/span><\/p>\n

            Watch the sky in the early morning. Do you see any planet? What is its name? Find out with the help of your teachers.
            \nAim :
            \n1. Most of the planets cannot be seen in normal sky.
            \n2. Few planets can be seen during some specific period in the night sky.
            \n3. Mercury, closest to the sun can be seen from the earth.
            \n4. Venus is also seen few days in a year.
            \n5. Uranus may be also seen on odd days in October.<\/p>\n

            \"Samacheer<\/p>\n

            ACTIVITY – 4<\/span><\/p>\n

            Prepare a list of Indian satellites from Aryabhatta to the latest along with their purposes.
            \nS.No. Name of satellite Year Purpose
            \n\"E:\\jyothi\\images\\2\\Samacheers<\/p>\n

            9th Science Guide Universe Additional Important Questions and Answers<\/h3>\n

            I. Choose the correct answer :<\/span><\/p>\n

            Question 1.
            \nThe Geocentric model of universe was proposed by ……………
            \n(a) Tyago Brane
            \n(b) Kepler
            \n(c ) Ptolemy
            \n(d) Copernicus
            \nAnswer:
            \nptolemy<\/p>\n

            Question 2.
            \nThe total area of observable universe is about light-years.
            \n(a) 9.3 billion
            \n(b) 93 billion
            \n(c) 93 million
            \n(d) 9.3 million
            \nAnswer:
            \n93 billion<\/p>\n

            Question 3.
            \nAll the atoms together only make up ______ percent of universe.
            \n(a) 3
            \n(b) 4
            \n(c) 5
            \n(d) 2
            \nAnswer:
            \n(b) 4<\/p>\n

            \"Samacheer<\/p>\n

            Question 4.
            \nThe milky way galaxy is ………………in shape.
            \n(a) Elliptical
            \n(b) Circular
            \n(e) Spiral
            \n(d) Irregular
            \nAnswer:
            \n(c) spiral<\/p>\n

            Question 5.
            \nStars are built by ____ gases.
            \n(a) Hydrogen
            \n(b) Helium
            \n(e) Nitrogen
            \n(d) Oxygen
            \nAnswer:
            \n(a) Hydrogen<\/p>\n

            \"Samacheer<\/p>\n

            Question 6.
            \nThe process that takes place in the Sun is ………………
            \n(a) Nuclear Fission
            \n(b) Spallation
            \n(c) Nuclear Fusion
            \n(d) None of these
            \nAnswer:(c)
            \nNuclear Fusion
            \nQuestion 7.
            \nThe energy of the sun is radiated in the form of_____ Rays.
            \n(a) Ultraviolet
            \n(b) Infrared
            \n(e) neutron radiation
            \n(d) X-rays
            \nAnswer:
            \n(b) Infrared<\/p>\n

            \"Samacheer<\/p>\n

            Question 8.
            \nThe ____ colour is the most intense colour in solar radiation.
            \n(a) blue
            \n(b) red
            \nc) violet
            \n(d) yellow
            \nAnswer:
            \n(d) yellow<\/p>\n

            Question 9.
            \nAthe distance of the planet from the sun increases, the period of revolution ………………..
            \n(a) increases
            \nb) decreases
            \n(c) remains the same
            \n(d) a & b
            \nAnswer:
            \n(a) increases<\/p>\n

            \"Samacheer<\/p>\n

            Question 10.
            \nWhich among the planets has less length of a day?
            \n(a) Mercury
            \n(b) Uranus
            \n(c) Jupiter
            \n(d) Saturn
            \nAnswer:
            \n(c) Jupiter<\/p>\n

            Question 11.
            \nThe hottest planet on the solar system is ……………….
            \n(a) Venus
            \n(b) Mercury
            \n(c) Mars
            \n(d) Earth
            \nAnswer:
            \n(a) Venus<\/p>\n

            \"Samacheer<\/p>\n

            Question 12.
            \nWhich planet is known as Red Planet?
            \n(a) Venus
            \n(b) Saturn
            \n(c) Mars
            \n(d) Neptune
            \nAnswer:
            \n(c) Mars<\/p>\n

            Question 13.
            \nThe number of moons present in Saturn is ………………..
            \n(a) 20
            \n(b) 30
            \n(c) 50
            \n(d) 60
            \nAnswer:
            \n(d) 60<\/p>\n

            \"Samacheer<\/p>\n

            Question 14.
            \nThe planet having the longest summers and winters is ………………….
            \n(a) Saturn
            \n(b) Neptune
            \n(c) Uranus
            \n(d) Jupiter
            \nAnswer:
            \n(c) Uranus<\/p>\n

            Question 15.
            \nWindiest planet in the solar system ………………..
            \n(a) Neptune
            \n(b) Uranus
            \n(c) Saturn
            \n(d) Jupiter
            \nAnswer:
            \na) Neptune<\/p>\n

            \"Samacheer<\/p>\n

            Question 16.
            \nWhich among the planets does not have a moon?
            \n(a) Mars
            \n(b) Earth
            \n(c) Uranus
            \n(d) Mercury
            \nAnswer :
            \n(d) Mercury<\/p>\n

            Question 17.
            \nThe orbital velocity of the satellite depends on its ……………………
            \n(a) Shape of orbit
            \n(b) altitude
            \n(c) distance
            \n(d) All of these
            \nAnswer:
            \n(b) altitude<\/p>\n

            \"Samacheer<\/p>\n

            Question 18.
            \nWhich among the following statements is correct?
            \n(i) Meteors are attracted by the gravitational at force of earth.
            \n(ii) Meteors are travelling in low speeds.
            \n(iii) Most of Meteors are burnt by the heat generated by friction in atmosphere.
            \n(a) (i) & (ii)
            \n(b) (ii) & (iii)
            \n(c) (i) & (iii)
            \n(d) All of these
            \nAnswer:
            \n(c) (i) & (iii)<\/p>\n

            Question 19.
            \nThe first part of the ISS was launched by
            \n(a) Russian Soyuz
            \n(b) Russian Zarya
            \n(c) Russian Orbital
            \n(d) American Sputnik
            \nAnswer:
            \n(b) Russian Zarya<\/p>\n

            \"Samacheer<\/p>\n

            Question 20.
            \nThe time is taken by the sun to complete one revolution around the milky way
            \n(a) 250 million years
            \n(b) 200 million years
            \n(c) 225 million years
            \n(d) 240 million years
            \nAnswer:
            \n(c) 225 million years<\/p>\n

            Question 21.
            \nWhich of the following statements is correct?
            \nA. There are eight planets in our Solar System.
            \nB. Except Mars, all other planets revolve around the Sun in elliptical orbits.
            \n(a) A only
            \n(b) B only
            \n(c) Both A and
            \n(d) None
            \nAnswer:
            \n(a) A only<\/p>\n

            \"Samacheer<\/p>\n

            II. Fill in the blanks :<\/span><\/p>\n

            1. Sun is the star present in the galaxy called ………………
            \nAnswer:
            \nmilky way<\/p>\n

            2. The universe began with the start of a massive explosion called ……………..
            \nAnswer:
            \nBig Bang<\/p>\n

            3. Scientists believe that there are ……………… galaxies in the observable universe.
            \nAnswer:
            \none hundred billion (1011<\/sup>)<\/p>\n

            \"Samacheer<\/p>\n

            4. Our closest neighbouring galaxy is ……………
            \nAnswer:
            \nAndromeda<\/p>\n

            5.We can see nearly _______ stars with the naked eye in the dark night
            \nAnswer:
            \n3000<\/p>\n

            6. The brightness of stars depends on their _______ and _____ from the earth.
            \nAnswer:
            \nIntensity and distance<\/p>\n

            \"Samacheer<\/p>\n

            7. The Greek name for the Sun is …………………
            \nAnswer:
            \nHelios<\/p>\n

            8. The sun is believed to be more than ______ years ago
            \nAnswer:
            \n4.6 billion<\/p>\n

            9. The inner planets are also known as __________
            \nAnswer:
            \nRocky planets<\/p>\n

            \"Samacheer<\/p>\n

            10. The outer planets are also called as _____
            \nAnswer:
            \nGaseous planets<\/p>\n

            11. ______ is the brightest heavenly body in our night sky.
            \nAnswer :
            \nVenus<\/p>\n

            12. ______ is called as giant planet
            \nAnswer :
            \nJupiter<\/p>\n

            \"Samacheer<\/p>\n

            13. ________ is the only moon i\u00f1 the solar system with clouds.
            \nAnswer :
            \nTitan<\/p>\n

            14. Uranus is a ______ giant
            \nAnswer:
            \ncold gas<\/p>\n

            15. Pluto crosses the orbit of Neptune in every ______
            \nAnswer :
            \n248 years<\/p>\n

            \"Samacheer<\/p>\n

            16. The biggest asteroid is …………………
            \nAnswer :
            \nCeres<\/p>\n

            17. Satellites move around the planets due to ………….. and ……………… force.
            \nAnswer :
            \ngravit\u00fd, the centripetal<\/p>\n

            18. The ratio of____ of the periods of any two planets is equal to the ratio of their semi-major axis from the Sun.
            \nAnswer :
            \nsquares, cubes<\/p>\n

            \"Samacheer<\/p>\n

            19. The temperature of the star is determined by ______
            \nAnswer :
            \nColour<\/p>\n

            20. ……………… is the only moon in the solar system that moves in the opposite direction to
            \nthe direction in which its planet spins.
            \nAnswer:
            \nTriton<\/p>\n

            \"Samacheer<\/p>\n

            III. Match the following:<\/span><\/p>\n

            (I)<\/p>\n\n\n\n\n\n\n
            1.Mercury<\/td>\na) Hottest planet<\/td>\n<\/tr>\n
            2.Saturn<\/td>\nb) Greenish star<\/td>\n<\/tr>\n
            3.Neptune<\/td>\nc) Rocky planet<\/td>\n<\/tr>\n
            4.Venus<\/td>\nd) Lightest planet<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

            Answer:
            \n1-c,2-d,3-b,4-a<\/p>\n

            (II)<\/p>\n\n\n\n\n\n\n
            1.Mars<\/td>\na) Bluish-green planet<\/td>\n<\/tr>\n
            2.Jupiter<\/td>\nb) Cold gas giant<\/td>\n<\/tr>\n
            3. Earth<\/td>\nc) Giand planet<\/td>\n<\/tr>\n
            4. Uranus<\/td>\nd) Red planet<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

            Answer:
            \n1-d,2-c,3-a,4-b<\/p>\n

            \"Samacheer<\/p>\n

            (III)<\/p>\n\n\n\n\n\n\n
            1. Ganymede<\/td>\na) Neptune<\/td>\n<\/tr>\n
            2. Triton<\/td>\nb) Jupiter<\/td>\n<\/tr>\n
            3. Titan<\/td>\nc) Mars<\/td>\n<\/tr>\n
            4. Phobas<\/td>\nd) Saturn<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

            Answer:
            \n1-b,2-a,3-d,4-c,
            \n(IV)<\/p>\n\n\n\n\n\n\n\n\n\n
            1. Jupiter<\/td>\na)17.2 hours<\/td>\n<\/tr>\n
            2. Mercury<\/td>\nb)10.7 hours<\/td>\n<\/tr>\n
            3. Venus<\/td>\nc) 87.97 days<\/td>\n<\/tr>\n
            4. Saturn<\/td>\nd) 9 hours 55 min<\/td>\n<\/tr>\n
            5. Mars<\/td>\ne) 243 days<\/td>\n<\/tr>\n
            <\/td>\nf) 87.97 days<\/td>\n<\/tr>\n
            <\/td>\ng) 24 hours 37 min<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

            Answer:
            \n1-d,2-c,3-e,4-b,5-g<\/p>\n

            \"Samacheer<\/p>\n

            IV. State whether true or false. If false, correct the statement:<\/span><\/p>\n

            1. The basic constituent of the universe is the luminous matter.
            \nAnswer:
            \nTrue.<\/p>\n

            2. The important thing about universe is that it is currently shrinking.
            \nAnswer:
            \nFalse.
            \nCorrect statement: The important thing about the universe is that it is currently expanding.<\/p>\n

            3. All the matter in the universe is made up of hydrogen and helium.
            \nAnswer:
            \nTrue.<\/p>\n

            \"Samacheer<\/p>\n

            4. Stars also appear to be in different colours depending on their composition of Gases.
            \nAnswer:
            \nFalse.
            \nCorrect statement: Stars also appear to be in different colours depending on their temperature.<\/p>\n

            5. The planets are revolving around the sun because of the gravitational force of attraction between them.
            \nAnswer:
            \nTrue.<\/p>\n

            6. The rotation of the sun near the poles takes around 25.4 days.
            \nAnswer: False.
            \nCorrect statement: The rotation of the Sun near the poles takes around 36 days.<\/p>\n

            \"Samacheer<\/p>\n

            7. Mercury is a special planet from the Sun, almost the same size as Earth.
            \nAnswer:
            \nFalse.
            \nCorrect statement: Venus is a special planet from the Sun, almost the same size as Earth.<\/p>\n

            8. The axis of rotation of the Earth is perpendicular to the plane of its orbit.
            \nAnswer:
            \nFalse.
            \nCorrect statement: The axis of rotation of the Earth is not perpendicular to the plane of its orbit.<\/p>\n

            9. Pole star is not visible from the southern hemisphere.
            \nAnswer:
            \nTrue.<\/p>\n

            \"Samacheer<\/p>\n

            10. Comets revolve around the Sun in highly spiral orbits.
            \nAnswer:
            \nFalse.
            \nCorrect statement: Comets revolve around the Sun in highly elliptical orbits.<\/p>\n

            11. The distance between Saturn and Uranus is about 10 times that between Earth and Mars.
            \nAnswer:
            \nFalse.
            \nCorrect statement: The distance between Saturn and Uranus is about 20 times that between Earth and Mars.<\/p>\n

            \"Samacheer<\/p>\n

            V. Assertion and Reason type questions :<\/span><\/p>\n

            Mark the correct choice as :
            \n(a) If both assertion and reason are true and Reason is the correct explanation of Assertion.
            \n(b) If both assertion and reason are true but reason is not the correct explanation of assertion. ,
            \n(c) If assertion is true but reason is false.
            \n(d) If assertion is false but reason is true.<\/p>\n

            Question 1.
            \nAssertion: Earth appears bluish-green.
            \nReason: This is due to the reflection of light from water and land mass on its surface.
            \nAnswer:
            \n(a) If both assertion and reason are true and Reason is the correct explanation of Assertion.<\/p>\n

            Question 2.
            \nAssertion: Sun is a medium-sized star.
            \nReason: Sun is situated at the centre of the solar system.
            \nAnswer:
            \n(b) Both assertion and reason are true but the reason is not the correct explanation of the assertion<\/p>\n

            \"Samacheer<\/p>\n

            Question 3.
            \nAssertion : The outer planets are called as Terrestial Planets.
            \nReason : Outer planets are made up of hydrogen, helium and other gases in huge amounts and have very dense atmospheres.
            \nAnswer:
            \n(d) Assertion is false but reason is true
            \nAssertion : The outer planets are called as Gas giants.<\/p>\n

            Question 4.
            \nAssertion : The period of revolution of a satellite around a planet is directly proportional to the radius of the orbit of the satellite.
            \nReason : Artificial satellites do not follow Kepler\u2019s Laws of motion.
            \nAnswer:
            \n(c) Assertion is true but reason is false
            \nReason : Artificial satellites follow Kepler\u2019s laws of motion.<\/p>\n

            \"Samacheer<\/p>\n

            Question 5.
            \nAssertion : At the pole, the value of acceleration due to gravity (g) is greater than equator.
            \nReason : Earth rotates on its axis in addition to revolving around the sun.
            \nAnswer:
            \n(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion<\/p>\n

            VI. Very Short Answer questions :<\/span><\/p>\n

            Question 1.
            \nWhat is the universe?
            \nAnswer:
            \nThe collection of all the things that exist in space is known as the universe.<\/p>\n

            Question 2.
            \nWhat is a galaxy?
            \nAnswer:
            \nA galaxy is a massive collection of gas, dust and billions of stars and their solar systems.<\/p>\n

            \"Samacheer<\/p>\n

            Question 3.
            \nHow are galaxies classified?
            \nAnswer:
            \nDepending on their appearance, galaxies are classified as<\/p>\n

              \n
            • Spiral,<\/li>\n
            • Elliptical, (or)<\/li>\n
            • Irregular.<\/li>\n<\/ul>\n

              Question 4.
              \nWhy is our galaxy called Milky way?
              \nAnswer:
              \nOur galaxy is called milky way galaxy, because it appears as a Milky band of light in the sky.<\/p>\n

              Question 5.
              \nWhat is an orbit?
              \nAnswer:
              \nA definite curved path in which a planet revolves around the sun is called an orbit.<\/p>\n

              \"Samacheer<\/p>\n

              Question 6.
              \nDefine Period of rotation.
              \nAnswer:
              \nThe time taken by a planet to complete one rotation is called its period of rotation.<\/p>\n

              Question 7.
              \nGive a reason for changes of seasons on Earth.
              \nAnswer:<\/p>\n

                \n
              • Earth is not perpendicular to the plane of its orbit.<\/li>\n
              • This tilt is responsible for the change of seasons on earth.<\/li>\n<\/ul>\n

                \"Samacheer<\/p>\n

                Question 8.
                \nMention the factors responsible for motion of satellite.
                \nAnswer:<\/p>\n

                  \n
                • Gravity and<\/li>\n
                • The centripetal force are the factors responsible for motion of satellite<\/li>\n<\/ul>\n

                  Question 9.
                  \nWhat is a geostationary orbit?
                  \nAnswer:
                  \nA satellite stays in a fixed position relative to a point on Earth’s surface. That is, the satellite stays over the same spot all the time. This kind of orbit is called “Geostationary Orbit”.<\/p>\n

                  Question 10.
                  \nHow is eye-tracking technology helpful?
                  \nAnswer:
                  \nEye-tracking technology is helping disabled people with limited movement and speech.<\/p>\n

                  \"Samacheer<\/p>\n

                  Question 11.
                  \nWhat is a cosmic year?
                  \nAnswer:
                  \nThe sun travelling at a speed of 250 km per second (9 lakhs km\/h) takes about 225 million years to complete one revolution around the Milky Way. This period is called a cosmic year.<\/p>\n

                  Question 12.
                  \nWhy are we able to see the Moon even though it is not a luminous body?
                  \nAnswer:
                  \nare able to see the moon, because it reflects the light of the Sun<\/p>\n

                  \"Samacheer<\/p>\n

                  VII. Answer briefly :<\/span><\/p>\n

                  Question 1.
                  \nWrite notes on the Milky Way.
                  \nAnswer:<\/p>\n

                    \n
                  1. Milky Way galaxy is spiral in shape.<\/li>\n
                  2. It is made up of approximately 100 billion stars.<\/li>\n
                  3. Its diameter is 1,00,000 light years.<\/li>\n
                  4. Our solar system is 25,000 light-years away from the centre of our galaxy.<\/li>\n<\/ol>\n

                    Question 2.
                    \nHow does a planet differ from a star?
                    \nAnswer:<\/p>\n\n\n\n\n\n
                    Star<\/td>\nPlanet<\/td>\n<\/tr>\n
                    1. Star is luminous body (emit their own light).<\/td>\nPlanet is a non-luminous body, (does not emit light). table<\/td>\n<\/tr>\n
                    2. It revolves in the galaxy-without any centre.<\/td>\nPlanet revolves around the star.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                    \"Samacheer<\/p>\n

                    Question 3.
                    \nBriefly explain (i) brightness (ii) colour of star.
                    \nAnswer:
                    \nBrightness of star:
                    \nThe brightness of a star depends upon their intensity and distance from the earth. Colour of star:<\/p>\n

                      \n
                    1. The colour of the stars depends on their temperature.<\/li>\n
                    2. Hot stars are white or blue.<\/li>\n
                    3. Cooler stars are orange or red in colour.<\/li>\n<\/ol>\n

                      Question 4.
                      \nWhat is a constellation?
                      \nAnswer:<\/p>\n

                        \n
                      1. A group of stars forming an imaginary outline or meaningful pattern on the space is called a constellation.<\/li>\n
                      2. They represent an animal, mythological person or creature or an object.<\/li>\n
                      3. \"Samacheer<\/li>\n<\/ol>\n

                        Question 5.
                        \nHow is life on earth supported?
                        \nAnswer:<\/p>\n

                          \n
                        1. Life on earth is supported by Sun.<\/li>\n
                        2. Solar energy from the Sim has supported and sustained terrestial existence on Earth since the beginning of time.<\/li>\n<\/ol>\n

                          Question 6.
                          \nWrite short notes on Asteroids.
                          \nAnswer:<\/p>\n

                            \n
                          1. \n
                              \n
                            1. Half a million pieces of rocks that were left over when the planets were formed are called Asteroids.<\/li>\n<\/ol>\n<\/li>\n
                            2. Asteroids revolve around the Sun.<\/li>\n
                            3. Asteroids can only be seen through large telescope.<\/li>\n
                            4. The biggest asteriod is Ceres.<\/li>\n<\/ol>\n

                              \"Samacheer<\/p>\n

                              Question 7.
                              \nDifferentiate Meteors and Meteorites?
                              \nAnswer:<\/p>\n\n\n\n\n
                              Meteors<\/td>\nMeteorites<\/td>\n<\/tr>\n
                              Small pieces of rocks that are burnt up by the heat generated due to friction in the Earth’s atmosphere.<\/td>\nBigger pieces of rocks that are not completely burnt by heat and fall on the surface of the Earth.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                              Question 8.
                              \nWrite down the formula of orbital velocity.
                              \nAnswer:
                              \nv = \\(v=\\sqrt{\\frac{\\mathrm{GM}}{(\\mathrm{R}+h)}}\\)
                              \nwhere v = Orbital velocity.
                              \nG = Gravitational constant. (6.673 \u00d7 10-11<\/sup>Nm 2<\/sup>kg-2<\/sup>
                              \nM = Mass of the Earth (5.972 \u00d7 1024<\/sup>kg)
                              \nR = Radius of Earth (6371 km)
                              \nh = Height of th\u00e9 satellite from the surface of the Earth.<\/p>\n

                              \"Samacheer<\/p>\n

                              Question 9.
                              \nWrite short notes on Halley\u2019s comet.
                              \nAnswer:<\/p>\n

                                \n
                              1. Halley\u2019s comet is a periodical comet.<\/li>\n
                              2. It appears after nearly ever\u00fd 76 years.<\/li>\n
                              3. It was last seen in 1986 and will next be seen in 2062<\/li>\n<\/ol>\n

                                Question 10.
                                \nMention the uses of Robotic arms.
                                \nAnswer:
                                \nRobotic arms<\/p>\n

                                  \n
                                1. Helps in removing inoperable tumours.<\/li>\n
                                2. Takes biopsies with great accuracy.<\/li>\n
                                3. Helpful in breast cancer detection and treatment.<\/li>\n
                                4. Helpful in the development of improved vaccines.<\/li>\n<\/ol>\n

                                  \"Samacheer<\/p>\n

                                  VIII. Answer In detail:<\/span><\/p>\n

                                  Question 1.
                                  \nExplain the salient features of the Big Bang Theory.
                                  \nAnswer:
                                  \nAccording to the Big Bang Theory,<\/p>\n

                                    \n
                                  1. The universe was a hot dense matter.<\/li>\n
                                  2. 13.7 billion years ago, an explosion occurred.<\/li>\n
                                  3. All the matter is ejected in all directions in the form of galaxies.<\/li>\n
                                  4. The galaxies consist of stars which are held together by gravity.<\/li>\n
                                  5. The stars explode and planets are liberated throughout the Universe.<\/li>\n<\/ol>\n

                                    Question 2.
                                    \nHow is Sun formed according to Big Bang theory?
                                    \nAnswer:
                                    \nAccording to the Big Bang theory.<\/p>\n

                                      \n
                                    1. Hydrogen gas condensed to form huge clouds.<\/li>\n
                                    2. Some of the hydrogen gas was left free and started floating around. in our galax<\/li>\n
                                    3. The free-floating hydrogen gas concentrated and paved way for the formation Sun and solar system.<\/li>\n
                                    4. The Sun and solar system turned into a slowly spinning molecular cloud, composed of hydrogen and Helium molecules.<\/li>\n
                                    5. The clouds undergo compression due to gravity.<\/li>\n
                                    6. The excessive and high-speed spinning of cloud results in flattening into a giant disc.<\/li>\n<\/ol>\n

                                      \"Samacheer<\/p>\n

                                      Question 3.
                                      \nGive a comparative account of satellites and rings of planets.
                                      \nAnswer:
                                      \n\"Samacheer<\/p>\n

                                      IX. Numerical problems :<\/span><\/p>\n

                                      Question 1.
                                      \nThe Earth’s distance from the Sun is 149.6 \u00d7 106<\/sup>km and the period of Earth’s revolution is 1 year. Calculate the ratio of the squares of the periods to cubes of the major axis.
                                      \nSolution :
                                      \nSemi major axis from sun, R = 149.6 \u00d7 106<\/sup> km.
                                      \nPeriod of Earth, T = 1 year.
                                      \nThe ratio = \\(\\frac{T^{2}}{R^{3}}=\\frac{(1)^{2}}{\\left(149.6 \\times 10^{6}\\right)^{3}}\\) = 2.98 \u00d710-25<\/sup> year2<\/sup> \/ km 3<\/sup>.<\/p>\n

                                      \"Samacheer<\/p>\n

                                      Question 2.
                                      \nThe mean distance of Earth from the Sun is 149.6 \u00d7 106<\/sup> km and the mean distance of mercury from the sun is 57.9\u00d7 106<\/sup>km. The period of Earth\u2019s revolution is 1 year. What is the period of Mercury\u2019s revolution? .
                                      \nSolution: Given
                                      \n1. Mean distance of Earth from Sun, r1 = 149.6 \u00d7 10 6<\/sup>
                                      \n2. Mean distance of Mercury from sun, r2 = 57.9 \u00d7 106<\/sup>
                                      \n3. The period of Earth\u2019s revolution, T1 = 1 year
                                      \n4. The period of Mercury\u2019s revolution, T2 = ?
                                      \nAccording to Keplar\u2019s Third Law
                                      \n\"Samacheer
                                      \n\"Samacheer
                                      \nQuestion 3.
                                      \nCalculate the speed and period of revolution of satellite orbiting at a height 700 km above the Earth\u2019s surface.
                                      \nSolution:
                                      \nGiven: 1. Height of th Satellite, h = 700 km = 700 x 103 m
                                      \nWe Know: 2. Gravitational constant G = 6.673 \u00d7 0-11<\/sup> Nm2 kg-2<\/sup>
                                      \n3. Mass of the Earth, M = 5.972 \u00d7 1024 kg
                                      \n4. Radius of Earth, R = 6371 km = 6371 \u00d7 103<\/sup> m
                                      \nFormula (R + h) = (6371 + 700)km = 7071 km
                                      \n= 7071 \u00d7 103<\/sup>m=0.7071 \u00d7 107<\/sup>m
                                      \n\"Samacheer<\/p>\n

                                      Period of Revolution T = 5.9 15 \u00d7 103 <\/sup>s
                                      \n= 5915 sec. (or) 98 min 35 sec.<\/p>\n","protected":false},"excerpt":{"rendered":"

                                      Tamilnadu State Board New Syllabus Samacheer Kalvi 9th Science Guide Pdf Chapter 9 Universe Text Book Back Questions and Answers, Notes. Tamilnadu Samacheer Kalvi 9th Science Solutions Chapter 9 Universe 9th Science Guide Universe Text Book Back Questions and Answers I. Choose the correct answer: Question 1. Who proposed the heliocentric model of the universe? …<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[3],"tags":[],"class_list":["post-23006","post","type-post","status-publish","format-standard","hentry","category-class-9"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/23006"}],"collection":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/comments?post=23006"}],"version-history":[{"count":1,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/23006\/revisions"}],"predecessor-version":[{"id":41217,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/posts\/23006\/revisions\/41217"}],"wp:attachment":[{"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/media?parent=23006"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/categories?post=23006"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/samacheerkalvi.guide\/wp-json\/wp\/v2\/tags?post=23006"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}