Question

why work contains only cosine?​

Answer 1

Answer:

Work is done by a force when it moves and, perhaps surprisingly, not just by it acting.

So sitting on a chair or a force just acting to change the direction of a velocity need do not work.

The amount of work done is the force times the distance moved in the direction of its line of action, or equivalently, the amount of force in the direction of movement times the movement.

Both result in the formula work = force x distance moved x cos(angle between line of force and line of action).

So for example, though the sun’s influence causes planets to orbit it no work is done unless the planet moves towards or away from the sun!

Answer 2

Answer:

The amount of work done is the force times the distance moved in the direction of its line of action, or equivalently, the amount of force in the direction of movement times the movement. Both result in the formula work = force x distance moved x cos(angle between line of force and line of action).