A block of mass 4 kg is kept on ground. The co-efficient of friction between the block and the ground is 0.80. an external force of magnitude 30 N is applied parallel to the ground. The resultant force exerted by the ground on the block is `(g=10m//x^(2))`

Options

A. 40N
B. 30N
C. 0N
D. 50N

Answer

D

Explanation

N=mg=40
`(f_(s))_(max)=muN=(0.8) (40)=32`
`f_(S)=ext` force =30
`R^(2)=N^(2)+f_(s)^(2)=(50)^(2)`
`:. R=50 Nt`.