Calculate the power of an electric motor that can lift $800 \, kg$ of water to store in a tank at a height of $1500 \, cm$ in $20 \, s$. $(g = 10 \, m s^{-2})$ (in $, kW$)

Does work done depend upon the velocity of the body?

$A$ rocket is moving up with a velocity $v$. If the velocity of this rocket is suddenly tripled,what will be the ratio of the initial kinetic energy to the final kinetic energy?

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

$A$ $2 \, m$ high person is holding a $25 \, kg$ trunk on his head and is standing at a roadways bus-terminus. How much work is done by the person (in $, J$)?

$(a)$ What is meant by mechanical energy? State its two forms. State the law of conservation of energy. Give an example in which we observe a continuous change of one form of energy into another and vice-versa.
$(b)$ Calculate the amount of work required to stop a car of $1000 \, kg$ moving with a speed of $72 \, km \, h^{-1}$.