Answer
Hi,
The forces are; weight (gravity), Normal/centripetal force and friction. Force due to gravity is constant where as friction and centripetal are not.
Explanation
Weight is constant, given by the force of gravity on the object. The centripetal force is a function of the angles occurring between the velocity vector and the weight vector that is at right angle with the perpendicular line drawn from the surface. Friction is a function of the centripetal force thus it also varies.
Hope this helps!
Answer:

Explanation:
Using the conservation of energy we have:

Let's solve it for v:

So the speed at the lowest point is 
Now, using the conservation of momentum we have:

Therefore the speed of the block after the collision is 
I hope it helps you!
Answer:
non-accelerated movement
velocity versus time a horizontal straight line.
distance versus time gives a horizontal straight line.
accelerated motion
graph of velocity versus time s an inclined line and the slope
graph of distance versus time is a parabola of the form
Explanation:
In kinematics there are two types of steely and non-accelerated movements
In a the velocity of the body is constant therefore a speed hook against time gives a horizontal straight line.
A graph of distance versus time is a straight line whose slope is the velocity of the body
x = v t
In an accelerated motion the velocity changes linearly with time, so a graph of velocity versus time is an inclined line and the slope is the value of the acceleration of the body
v = v₀ + a t
A graph of distance versus time is a parabola of the form
x =v₀ t + ½ a t²