Question

It is the case 1 of work done positive.. I understand but why here in figure it is saying...
cos0 degree=1..?
I mean why here it uses cos why not tan..??
and cos=base/hypotenus..!!
so what it wants to conclude from this... please just Tell me why it uses cos here why not tan or any other sign??
I will mark you as brainlist promise but right answer!​

Answer 1

Suppose that, force is given to a body as follows :-

A  ▬▬▬▬▬▬▬➤

       Force →→

As the force is only given towards right side and any other external force is not applied on it, body A moves towards right side. So, here displacement is in the direction of force.

Body A displaces towards right side. Then we can say that, A displaces towards x-axis. If the angle formed with the plane is θ, then the "x-component" is taken as cosθ, and the "y-component" is taken as sinθ.

For the above example, the body is directly displacing in the x-axis, so dividing it into components is not required. So,

cosθ = cos 0° = 1

Here, θ = 0°

___________________

We can also say that, displacement is a vector quantity. So, work done is also a vector quantity. Now, for vectors, the value can also be negative. If the work on the same direction, their magnitude is positive. So, here, force and displacement, being vector quantities, work in the same direction, then the overall work done is positive.

For they work in opposite direction, the work done changes its sign no negative.