A block of mass 15 kg is place over a frictionless horizontal surface. Another block of mass 10 kg is place over it, that is connected with a light string passing over two pulleys fasted to the 15 kg block. A force F 80N is applied horizontally to the string. Friction coefficient between two blocks is 0.6. T portion of the string between 10 kg block and the upper pulley is horizontal. Pulley,string and connecting ro are massless. (Take `g=10 m//s^2`)

If applird force F=120 N, then magnitude of acceleration of 15 kg block will be

Options

A. `8 m//s^2`
B. `4 m//s^2`
C. `3.2 m//s^2`
D. `4.8 m//s^2`

Answer

B

Explanation

F=120N, then there will be slipping
For 10kg block,
`120-60=10a" "implies a=6m//s^2`
`"For 15kg block,"" "60=15a" "implies a=4 m//s^2`