A block `A` with mass 100kg is resting on another block `B` of mass 200kg. As shown in figure a horizontal rope tied to a wall hold it. The coefficient of friction between `A` and `B` is `0.2` while coefficient of friction between `B` and the ground is `0.3` . the minimum required force `F` to start moving `B` will be.

Options

A. `900N`
B. `100N`
C. `1100N`
D. `1200N`

Answer

C

Explanation

`F=f_(AB)+f_(BG)`
`=mu_(AB)m_(a)g+mu_(BG)(m_(A)+m_(B))g`
`=0.2xx100xx10+0.3(300)xx10`
`=200+900=1100N` .