Q2 of 26 Page 28

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

Option (ii) gravitational force and (iii) Frictional Force

Explanation:


Work done by a force on an object is negative when direction of force acting on object and displacement of object are in exactly opposite direction, or direction of displacement makes 1800 with direction of applied force because we know work done on an object due to a force is given by relation


W = F× s × cos

More from this chapter

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2

Choose one or more correct alternatives.

Which of the forces involved in dragging a heavy object on a smooth, horizontal surface, have the same magnitude?


i. the horizontal applied force


ii. gravitational force


iii. reaction force in vertical direction


iv. force of friction

 2

Choose one or more correct alternatives.

Power is a measure of the ...….


i. the rapidity with which work is done


ii. amount of energy required to perform the work


iii. The slowness with which work is performed


iv. length of time

 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.

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