A particle of mass 1 kg slides in a horizontal circle of radius 20 m with a constant speed of `1 m//s.` The only forces in the vertical direction acting on the particle are its weight and the normal reaction, however no information is available about the forces in the horizontal plane. Over a period of time whole energy dissipated due to work done by friction is conducted to ground and simultaneously radiated to surround. If the coefficient of friction is `mu =0.5.` Then (Take `g =10 m//s^(2):

Options

A. The magnitude of frictional force acting on the block must be 5 N
B. The frictional force must be in tangential direction.
C. The frictional force must be towards the centre.
D. No comment can be made about the direction or magnitude of friction based on the given data.

Answer

A, B

Explanation

Here there must be some force providing the centripetal acceleration for circular motion but we are not concerned about it any option.As the bodyis sliding the kinetic friciton on the body must be `mumg = 5N` and it will act in tangential direction i.e. oppositeto directionof velocity.