When do we say that work is done? - Science

A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 10.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?

Write an expression for the work done when a force is acting on an object in the direction of its displacement.

Define 1 J of work.

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?

What is the kinetic energy of an object?

Write an expression for the kinetic energy of an object.

The kinetic energy of an object of mass, m moving with a velocity of 5 m s–1 is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?

What is power?

Define 1 watt of power.

A lamp consumes 1000 J of electrical energy in 10 s. What is its power?