Let a constant force, F act on an object. Let the object be displaced through a distance, s in the direction of the force. Let W be the work done. We define work to be equal to the product of the force and displacement. Work done = force × displacement
W = F s ..(1)
Thus, work done by a force acting on an object is equal to the magnitude of the force multiplied by the distance moved in the direction of the force. Work has only magnitude and no direction. in Eq.(1), if F = 1 N and s = 1 m then the work done by the force will be 1 N m. Here the unit of work is newton metre (N m) or joule (J). Thus 1 J is the amount of work.
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?
In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
An object thrown at a certain angle to the ground moves in a curved path and falls back to the ground. The initial and the final points of the path of the object lie on the same horizontal line. What is the work done by the force of gravity on the object?
A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (see the given figure). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
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?