Question

A bike rider wishes to circle inside a wooden vertical cylinder of radius 5m with a speed of $5\sqrt{5}$m/s. The minimum value of coefficient of friction between tyres and walls of the well is

• A. 0.1
• B. 0.5
• C. 0.7
• D. 0.4

Answer 1

The correct option is D 0.4

The centripetal force is provided by the normal force in this problem
Thus, normal force N= $m{v}^2/R$ and
Frictional force = $\mu N$
If frictional force is balanced by the weight of the object, then the bike will stay on the track.
Equating, we get, $\mu =rg/v^2$. Substituting the values, we get, $\mu =5\times 10/125=0.4$
The correct option is (d)