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A force F required to keep a 5 kg mass moving round a cyc...

A force F required to keep a 5 kg mass moving round a cycle of radius 3.5 m at a speed of 7 ms-1. What is the speed, if the force is tripled?

A.

4.0 ms-1

B.

6.6 ms-1

C.

12.1 ms-1

D.

21.0 ms-1

Correct answer is C

The force which is centripetal
F = MV2R
=5 x 723.5
= 70

 

Since, force is 70 N when speed is 7m/s

Speed = ? when force 70N is trippled →  70 * 3 = 210N

210 = 5×v23.5
210 × 3.5 = 5 * v^2
735 ÷ 5 = v2
v2 = 147
v =12.12m/s