$A$ crane pulls up a car weighing $500 \, kg$ to a vertical height of $4 \, m$. Calculate the work done by the crane. (in $J$)

State whether the following statement is true or false:
Work done by centripetal force is zero.

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

$A$ block of mass $5 \,kg$ is lying on a frictionless table. $A$ force of $20 \,N$ is applied on it for $10 \,s$. Calculate its kinetic energy. (in $J$)

$A$ boy throws a rubber ball vertically upwards. What type of work is done: $(a)$ by the force applied by the boy,and $(b)$ by the gravitational force? Support your answer with reasons.

$A$ girl is carrying a school bag of $3 \, kg$ mass on her back and moves $200 \, m$ on a levelled road. The work done against the gravitational force will be $(g = 10 \, m \, s^{-2})$.