Block A and B of masses 5 kg and 10 kg are placed as shown in figure. If block A is pulled with 50 N. Find out acceleration of the A and B. If coefficient of friction between A and B is 0.5 and between B and ground is 0.4.

Options

A. 5.1 and 0
B. 4 and 0
C. 3 and 2
D. 3.2 and 5

Answer

A

Explanation

Limiting friction between A and B
`f_(1)mu_(1)R_(1)=0.5xx5g=24.5N`
Limiting friction between B and ground
`f_(2)=mu_(2)R_(2)=0.4xx15g=58.8 N`
For block A, `50-f_(1)=5xxa`
`implies 50-24.5=5xxa implies a=5.1 ms^(-2)`
For block B accelerating force `f_(1)=24.5 N` is less than limiting friction `f_(2)=58.8 N`

so, block B will remain at rest.