Give reasons. a. A stretched catapult has potential energy.
b A stone on ground has zero energy.
C. Rolling a drum is work against friction.
d. Lifting a stone is work against gravity.
e. Work and energy both have same unit.

A. A stretched catapult can do work when released so it must have potential energy.

b. A stone on the ground will not move on its own ever again so it has zero energy.

c. In order to roll an object there must be a friction force between the object and the ground (otherwise it will slide)

d. To lift a stone you must overcome the weight which is the force due to gravity.

e. Work and energy are both measured in Joules.