The speed of a particle is doubled,its kinetic energy:

An object of mass $5\,kg$ falls from a height of $5\,m$ above the ground. The loss of potential energy of the mass is:

How is work done by a force measured? $A$ porter lifts a luggage of $20 \, kg$ from the ground and puts it on his head $1.7 \, m$ above the ground. Find the work done by the porter on the luggage. $(g = 10 \, m s^{-2})$

$A$ man weighing $70 \,kg$ carries a weight of $10 \,kg$ to the top of a tower $100 \,m$ high. Calculate the work done.

What is the work done by the force of gravity in the following cases?
$(a)$ $A$ satellite moving around the Earth in a circular orbit of radius $35000 \, km$.
$(b)$ $A$ stone of mass $250 \, g$ is thrown up to a height of $2.5 \, m$.

The velocity of a body moving in a straight line is increased by applying a constant force $F$ for some distance in the direction of the motion. Prove that the increase in the kinetic energy of the body is equal to the work done by the force on the body.