A body of mass 5 kg moves along a straight line under the action of a variable force. From x = 0 to x = 4 m, the force acts in the direction of displacement and increases linearly from 0 N to 20 N. From x = 4 m to x = 6 m, the motion of the body reverses while the force acts in forward direction. From x = 6 m to x = 10 m, the force becomes negative acting opposite to the original direction of motion. Calculate the net work done by the force on the body.

According to the work energy theorem, the increase in the kinetic energy of a moving body is equal to …………… by a force acting in the direction of the moving body.

1. displacement
2. velocity
3. acceleration
4. work done

The velocity of a moving cart is reduced to $\dfrac{1}{3}$rd the initial velocity. Its kinetic energy is reduced by :

1. $\dfrac{1}{2}$

2. $\dfrac{1}{3}$

3. $\dfrac{1}{6}$

4. $\dfrac{1}{9}$

A body of mass 10 kg is moving with a velocity of 20 m/s. The mass of the body is doubled and velocity is halved. Its initial kinetic energy is:

1. 200 J
2. 4000 J
3. 2000 J
4. 1000 J