A large drum having radius R is spinning around its axis with angular velocity , as shown in figure. The minimum value of so that a body of mass M remains stuck to the inner wall of the drum, taking the coefficient of friction between the drum surface and mass M as , is : [figure]
- 2g R
- g2 R
- gR
- g R
Answer
(4) g R
Solution
The normal reaction of the wall provides the centripetal force:
N = M 2 R
Friction (upward) must balance the weight:
f = Mg N = M 2 R
2 g R
= g R
Answer: (4)