Question

What do you understand from work? If the direction of displacement is different from the direction of the force then how do you calculate the work done? Explain with suitable examples.

Answer 1

In physics, if we apply force on a body then because of the influence of that force that body gains or loses some energy via it will be displaced from its original point. Applied force on a body can also be referred to as energy transfer to or from a body.

Complete step by step answer:
Work: It is the measure of energy transfer that happens when a body moves some distance due to the effect of some external force.
Example of work: It can be if a person is moving from one point to another point. But if the initial and final position of a body is the same then that will mean there has been no displacement then the work done would be zero.
Work done $W = Fd\cos \theta$
Where W is the work done, F is the applied force, d is the displacement. The amount of work done by the force of one Newton in moving an object through a distance of one meter in the direction of the force gives 1 joule.
When the direction of displacement is different from the direction of force then the work done can be calculated through the angle between the direction of displacement and applied force. The one example is when you have to stop a large ball from rolling then you have to apply force opposite from the direction in which it is moving.

Note: According to the work-energy theorem, the sum of the work done on a system by all the forces acting on that body is equal to the change in the kinetic energy of that body.
The S. I. Unit of work done is Joule (J), also some other units of work done are foot-pound and erg
If the applied force on a body is opposite to the direction of the motion then the work done should be negative.