Answer:
fr = ½ m v₀²/x
Explanation:
This exercise the body must be on a ramp so that a component of the weight is counteracted by the friction force.
The best way to solve this exercise is to use the energy work theorem
W = ΔK
Where work is defined as the product of force by distance
W = fr x cos 180
The angle is because the friction force opposes the movement
Δk = –K₀
ΔK = 0 - ½ m v₀²
We substitute
- fr x = - ½ m v₀²
fr = ½ m v₀²/x
Here in first case both balls will exert electrostatic force on each other
due to this electrostatic force the two balls will repel each other
Apart from this there will be gravitational force on the two balls which is vertically downwards
Now here we know that as the electrostatic force of repulsion will increase between two balls then the angle between the two balls will be more as the horizontal force will separate the two balls
Part b)
As we decrease the charge on one ball then the net electrostatic force between two balls will decrease as we know that this force will depends on the product of two charges
so here the angle between the two balls will decrease and the two balls will come closer.
Also by the free body diagram of two balls we can see that all the forces on the balls are same so the angle made by the ball with the vertical is same for both the balls
so here the angle that ball l makes with the vertical will be equal to the angle that ball 2 makes with the vertical.
