A ball of mass 0.5 kg slows down from a speed of 5ms^-1 to 3ms^-1.Calculate the change in kinetic energy of the ball.

Q.

(a) Explain by an example what is meant by potential energy. Write down the expression for gravitational potential energy of a body of mass m placed at a height h above the surface of the earth.

(b) What is the difference between potential energy and kinetic energy?

(c) A ball of mass 0.5 kg slows down from a speed of 5 m/s to that of 3 m/s. Calculate the change in kinetic energy of the ball. State your answer giving proper units.

Q. Calculate the kinetic energy and potential energy of the ball half way up, when a ball of mass 0.1 kg is thrown vertically upwards with an initial speed of $20m{s}^{-1}$.

Q. Two mass-less strings of length $5m$ hang from the ceiling very near to each other as shown in the figure. Two balls $A$ and $B$ of masses $0.25kg$ and $0.5kg$ are attached to the string. The ball $A$ is released from rest at a height $0.45m$, as shown in the figure. The collision between two balls is completely elastic. Immediately after the collision, the kinetic energy of ball $B$ is $1J$. The velocity of the ball $A$, just after the collision is