IIT JEE , AIEEE Forum - Physics , Mechanics

loyalgooner

Imagine the circle to have the center as the origin and it is rotating about the origin in anti clockwise direction. Now suppose initially the particle is at right most point,say if the circle has radius r then the point is at (r,0), now here the centripetal force would act along negative x direction. Now as it comes to point to diametrically opposite point at (-r,0) the force changes direction and is in +ve X direction although the magnitude remains same coz its uniform circular motion.

So suppose the magnitude is F, so initially the centripetal force is -F i cap and then it becomes +F i cap, so difference = 2F i cap = 8N i cap

Thus F = 4 N.

Similarly initially the momentum is say -p j cap (anti clw motion) and final is +p j cap. So difference is 2p j cap = 2 kg m/s and so p = 1 kgm/s.

Now F = mv^2/r=4 and p=mv=1

Thus putting value of m=1/v in F we get v/r = 4 But v/r = omega

So omega w = 4 rad/s.

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