When a stone of mass $m$ falls through a vertical height $d$,the decrease in the gravitational potential energy is:

Can any object have mechanical energy even if its momentum is zero? Explain.

What is the work done by the force of gravity in the following cases?
$(a)$ $A$ satellite moving around the Earth in a circular orbit of radius $35000 \, km$.
$(b)$ $A$ stone of mass $250 \, g$ is thrown up to a height of $2.5 \, m$.

$A$ light and a heavy body have the same momentum. Which one will have greater kinetic energy?

When an arrow is shot from its bow,it has kinetic energy. From where does it get the kinetic energy?

$(a)$ How much work is done when a force of $1\, N$ moves a body through a distance of $1\, m$ in its direction?
$(b)$ Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.