Q.

A particle is moving on a circular path of 10 m radius. At any instant of time, its speed is 5 m s-1 and the speed is increasing at a rate of 2 m s-2. The magnitude of net acceleration at this instant is, the force acting on the particle is

1 mω2r→  
2 -mω2r→  
3 2mω2r→  
4 -2mω2r→  

Ans.

(2)

Given:  r→=Acosωt i^+Bsinωt j^

Velocity,  v→=dr→dt=ddt(Acosωt i^+Bsinωt j^)

                  =-Aωsinωt i^+Bωcosωt j^

Acceleration, a→=dv→dt=-Aω2cosωt i^-Bω2sinωt j^

a→=-ω2[Acosωt i^+Bsinωt j^]=-ω2r→

The force acting on the particle is

F→=ma→=m(-ω2r→)=-mω2r→