The coefficient of friction between the block and the horizontal surface is `mu`. The block moves toward right under action of horizontal force `F` (figure-a). Sometime later another force `P` is applied to the block making an angle theta (such that `tan theta`=`mu`) with vertical as shown in (figure-b). After application of force `P` , the acceleration of block shall.

Options

A. increase
B. decrease
C. remain same
D. information insufficient to draw inference

Answer

C

Explanation

The free body diagram of block in fig. b is as shown.
`N=mg+Pcostheta`
and acceleration of block
`a=(F+P sintheta-mu(mg+Pcostheta))/(m)`
`a=(F+P sintheta-(sintheta)/(costheta)(mg+Pcostheta))/(m)=(F-mumg)/(m)`
Hence P does not change acceleration.