Question

A block of metal is lying on the floor of a bus. The maximum acceleration which can be given to the bus so that the block may remain at rest, will be:

• A. ${\mu g}^2$
• B. $\mu g$
• C. $\mu /g$
• D. ${\mu }^{2}g$

Answer 1

Answer: (B)

Let $a$ be the acceleration of the bus. The contact between the metal block and the bus floor is due to the frictional force. The forces acting on the block are the inertia force and the frictional force. For equilibrium we have $ma=\mu mg\Rightarrow a=\mu g$ where $\mu$ is the friction coefficient in between block and the floor of bus.
Ans:(C)