Question 1 :
An electric heater is rated 1500 W. How much energy does it use in 10 hours?

Question 2 :
A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?

Question 3 :
Avinash can run with a speed of $8 ms^{-1}$ against the frictional force of 10 N, and Kapil can move with a speed of $3 ms^{–1}$ against the frictional force of 25 N. Who is more powerful and why?

Question 4 :
A girl pulls a trolley and the trolley moves through a distance. The girl has exerted a force on the trolley and it is displaced. Therefore, work is done.

Question 5 :
According to the law of conservation of energy, energy can only be transformed from one form to another; it can neither be created nor destroyed. The total energy before and after the transformation always remains constant.

Question 7 :
What is the formula of potential energy of an object ?

Question 8 :
An automobile engine propels a 1000 kg car (A) along a levelled road at a speed of $36 kmh^{–1}$.Now, suppose after travelling a distance of 200 m, this car collides with another stationary car (B) of same mass and comes to rest. Let its engine also stop at the same time. Now car (B) starts moving on the same level road without getting its engine started. Find the speed of the car (B) just after the collision.

Question 10 :
Calculate the work required to be done to stop a car of 1500 kg moving at a velocity of 60 km/h?