Which one of the following is not the unit of energy?

What happens to the kinetic energy when
$(i)$ the mass of the body is doubled at constant velocity?
$(ii)$ the velocity of the body is doubled at constant mass?
$(iii)$ the mass of the body is doubled but the velocity is reduced to half?

An object of mass $5\,kg$ falls from a height of $5\,m$ above the ground. The loss of potential energy of the mass is:

$(a)$ State the law of conservation of energy.
$(b)$ Establish the relation between the $SI$ unit of energy and the commercial unit of energy.
$(c)$ $A$ toy car is displaced through $5 \, m$ on the application of a force of $7 \, N$. Assuming the force acts on the object throughout the displacement,what is the work done in this case?

Give the formula for calculating work done. What is the $SI$ unit of work?

Identify the energy possessed by a rolling stone.