How are kinetic energy and momentum related?

$A$ light and a heavy body have equal kinetic energy. Which one is moving fast?

$A$ man of mass $60 \, kg$ runs up a flight of $30$ steps in $40 \, s$. If each step is $20 \, cm$ high,calculate the power of the man.

$A$ spring which has been kept compressed by tying its ends together is allowed to be dissolved in an acid. What happens to the potential energy of the spring?

Calculate the kinetic energy of a car of mass $750\, kg$ moving with a velocity of $54\, km h^{-1}$. Find the new kinetic energy of the car if a passenger of mass $50\, kg$ sits in the car.

State whether the following statement is true or false:
In order to get minimum work,the angle between force and displacement should be $90^{\circ}$.