A 2 kg block iks placed over a 4 kg block and both are plced on a smooth horizontal surfae. The coefficient of friction between the blocks is 0.20. Find theacceleration of the two blocks if a horizontal force os 12 N is applied to a. the upper block, b. the lower block. Take `g=10 m/s^2`.

Explanation

`R_1-2g=0`
`rarr R_1=2xx10=20`
2a+0.2R_1-12=0`
`rarr 2a+0.2(20)=12`
`rarr 2=12-4`
`rarr a=4m/s^2`
Again `4a-muR_1=0`
`rarr 4a=muR_1=0.2(20)=4`
`rarr a_1=1m/s^2`

`2 kg block has acceleration `4m/s^2 and that of 4 kg is `1 m/s^2`.
`ii R_1=2g=20`
`ma=muR_1=0`
a=0
`4a+0.2xx2xx10-12=0`
`rarr 4a+4=12`
`rarr 4a=8`
`a=2m/s^2`