Calculate the work required to be done to stop a car of $1500 \, kg$ moving at a velocity of $60 \, km/h$. (in $J$)

$A$ mass of $10\, kg$ is at a point $A$ on a table. It is moved to a point $B$. If the line joining $A$ and $B$ is horizontal,what is the work done on the object by the gravitational force? Explain your answer.

$A$ certain force acting on a $20 \, kg$ mass changes its velocity from $5 \, m \, s^{-1}$ to $2 \, m \, s^{-1}$. Calculate the work done by the force. (in $J$)

Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?

Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term 'work'.
$1$. Suma is swimming in a pond.
$2$. $A$ donkey is carrying a load on its back.
$3$. $A$ windmill is lifting water from a well.
$4$. $A$ green plant is carrying out photosynthesis.
$5$. An engine is pulling a train.
$6$. Food grains are getting dried in the sun.
$7$. $A$ sailboat is moving due to wind energy.

What is the kinetic energy of an object?