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?
We have,
Force exerted, F = 140 N
Displacement, s = 15 m
Therefore,
Work done, W = Fs
= 140 N x 15 m
= 2100 J.
Look at the activities listed below. Reason out whether or not work is done in the light of your understanding of the term ‘work’:
(i) Suma is swimming in a pond.
(ii) A donkey is carrying a load on its back.
(iii) A wind mill is lifting water from a well.
(iv) A green plant is carrying out photosynthesis.
(v) An engine is pulling a train.
(vi) Food grains are getting dried in the sun.
(vii) A sailboat is moving due to wind energy.
When do we say that work is done?
Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Define 1 Joule (J) of work.
