Three blocks of masses m, 3m and 5m are connected by massless strings and pulled by a force F on a frictionless surface as shown in the figure below. The tension P in the first string is 16N.

If the point of application of F is changed as given below.

The values of P' and Q' shall be

Options

A. 16N,10N
B. 10N,16N
C. 8N, 2N
D. None of these

Answer

A

Explanation

Let a be the common acceleration of the system
`therefore a=(F)/(m+3m+5m)=(F)/(9m)` .....(i)
`therefore P=(3m+5m)a`
`16=8ma (because P=16N("Given")]`
`a=(2)/(m)`
Substituting this value of a in eqn(i), we get F=18N

`P'=ma=2N`
`Q'=(3m+m)a=4ma=4xx2N=8N`
None of the given option is correct.