A block P of mass m is placed on horizontal frictionless plane. A second block of same mass m is placed on it and is connected to a spring of spring constant k, the two blocks are pulled by distance A. Block Q oscillates without slipping. What is the maximum value of frictional force between the two blocks.

Options

A. `kA`
B. `(KA)/(2)`
C. zero
D. `mu_(s)mg`

Answer

B

Explanation

For block `PK` friction will provide the meessary resorting force
`f_(max) = m omega^(2)A`
With `omega^(2) = (k)/(m+m) = (k)/(2m)`
Hence `f_(max) = m((k)/(2m)) A = (kA)/(2)`
So option (b) is correct