Q3 of 26 Page 28

Rewrite the following sentences using proper alternative.

The total energy of an object falling freely towards the ground …


i. decreases


ii. remains unchanged


iii. increases


iv. increases in the beginning and then decreases

Option (ii) remains unchanged

Explanation: Total energy of a body is sum of kinetic energy and potential energy, kinetic energy depends upon velocity of body, potential energy depends upon position of body(height from surface of earth in gravitational potential energy), they keep varying but their sum i.e. total energy always remains constant, potential energy and kinetic energy keeps on interconverting into each other but the total energy is conserved or unchanged as in accordance with law of conservation of energy, so in case of a freely falling body, speed of body keeps on increasing i.e. kinetic energy is increasing but height of body from ground is decreasing i.e. its potential energy keeps on decreasing , increase in kinetic energy is equal to decrease in potential energy , i.e. the net sum , Total energy of the object remains Same.


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2

Choose one or more correct alternatives.

While dragging or lifting an object, negative work is done by


i. the applied force


ii. gravitational force


iii. frictional force


iv. reaction force

 3

Rewrite the following sentences using proper alternative.

The potential energy of your body is least when you are …..


i. sitting on a chair


ii. sitting on the ground


iii. sleeping on the ground


iv. standing on the ground

 3

Rewrite the following sentences using proper alternative.

If we increase the velocity of a car moving on a flat surface to four times its original speed, its potential energy….


i. will be twice its original energy


ii. will not change


iii. will be 4 times its original energy


iv. will be 16 times its original energy.

 3

Rewrite the following sentences using proper alternative.

The work done on an object does not depend on ….


i. displacement


ii. applied force


iii. initial velocity of the object


iv. the angle between force and displacement.