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This force is centripetal force. it is the force that will hold the rider in the circular path and prevent him from skidding off. It is equal to the friction between the tyres and the road if no banking has been done on the road at the corner.
Answer:
Explanation:
Given
A is the area of circle with radius r

Differentiate w.r.t time

Also 

Explanation:
If we assume negligible air resistance and heat loss, we can assume that all of the Gravitational potential energy of the ball will turn into Kinetic energy as it falls toward the ground.
Therefore our Kinetic energy = mgh = (10kg)(9.81N/kg)(100m) = 9,810J.