s<\/sub> mg cos \u03b8<\/p>\nQuestion 11.
\nWhen the object is moving at a constant velocity on the rough surface _______.
\na) net force on the object is zero
\nb) no force acts on the object
\nc) only external force acts on the object
\nd) only kinetic friction acts on the object
\nAnswer:
\na) net force on the object is zero<\/p>\n
Question 12.
\nWhen an object is at rest on the inclined rough surface _______
\na) static and kinetic frictions acting on the object is zero
\nb) static friction is zero but kinetic friction is not zero.
\nc) static friction is not zero and kinetic friction is zero.
\nd) static and kinetic frictions are not zero.
\nAnswer:
\nc) static friction is not zero and kinetic friction is zero.<\/p>\n
Question 13.
\nThe centrifugal force appears to exist _______.
\na) only in inertial frames
\nb) only in rotating frames
\nc) in an accelerated frame
\nd) both in inertial and non-inertial frames
\nAnswer:
\nb) only in rotating frames<\/p>\n
<\/p>\n
Question 14.
\nChoose the correct statement from the following.
\na) Centrifugal and centripetal forces are action-reaction pairs.
\nb) Centripetal forces is a natural force.
\nc) Centrifugal force arises from the gravitational force.
\nd) Centripetal force acts towards the center and centrifugal force appears to act away from the center in a circular motion.
\nAnswer:
\nd) Centripetal force acts towards the center and centrifugal force appears to act away from the center in a circular motion.<\/p>\n
Question 15.
\nIf a person moving from pole to equator, the centrifugal force acting on him
\na) increase
\nb) decreases
\nc) remains the same
\nd) increase and then decreases
\nAnswer:
\na) increase<\/p>\n
<\/p>\n
II. Short Answer Questions:<\/span><\/p>\nQuestion 1.
\nExplain the concept of Inertia. Write two examples each for Inertia of motion, inertia of rest and inertia of direction.
\nAnswer:
\nThe inability of objects to move on its own or change its state of motion is called inertia. Inertia means resistance to change its state. There are three types of inertia:
\n1. Inertia of rest:
\nThe inability of an object to change its state of rest is called inertia of rest.
\nExample:<\/p>\n