Question

Given that a force ˆF acts on a body for time t, and displaces
the body by ˆd . In which of the following cases, the speed
of the body must not increase?
(a) F > d (b) F < d
(c) Fˆ = dˆ (d) Fˆ ^ dˆ

Answer 1

Here we are applying a force F at an angle of θ, if we resolve the force it becomes Fcosθ and Fsinθ.

We have displacement along Fcosθ 

We know that work-done is the product of force and displacement along the direction of the force.

Hence, 

work done=Fcosθ∗S.