State whether the following statement is true or false:
Kilowatt hour $(kWh)$ is the unit of power.

$(a)$ $A$ person is holding a bucket of water by applying a vertical force of $100 \, N$. He first moves a horizontal distance of $5 \, m$ and then climbs up through stairs a vertical distance of $10 \, m$. Calculate the total work done by the person on the bucket.
$(b)$ Establish the relationship between kinetic energy and momentum of a body.

$A$ man drops a $10 \, kg$ rock from the top of a $20 \, m$ ladder. What will be its kinetic energy when it reaches the ground? What will be its speed just before it hits the ground? (Take $g = 10 \, m s^{-2}$)

$(a)$ Define work. State two factors on which the magnitude of work depends.
$(b)$ $A$ car and a truck have the same speed of $30 \, m/s$. If their masses are in the ratio $1:3$,find the ratio of their kinetic energy.

State the type of energy transformation in the following cases: $(a)$ in a loudspeaker $(b)$ solar battery.

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