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?
- 4.0 ms-1
- 6.6 ms-1
-
12.1 ms-1
- 21.0 ms-1
The correct answer is: C
Explanation
The force which is centripetal
F = \(\frac{MV^2}{R}\)
=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 = \(\frac{5×v^2}{3.5}\)
210 × 3.5 = 5 * v^2
735 ÷ 5 = v\(^2\)
v\(^2\) = 147
v =12.12m/s
There is an explanation video available .