A block of mass 70kg is kept on a rough horizontal surface `(mu=0.4)` . A person is trying to pull the block by applying a horizontal force, but the block is not moving. The net contact force exerted by the surface on the block is `F` , then:

Options

A. `F = 280 N `
B. `F = 754 N `
C. `F = 700 N `
D. `700 N le F le 754 N`

Answer

D

Explanation

`N = 70 g = 700 N `

contact force `, F = sqrt ( N ^(2) + f ^(2))`
So `N le F le sqrt (N ^(2) + F _(1 ^(2))`
`700 le F le sqrt ( 700 ^(2) + 280 ^(2))`
`implies 700 N le F le 754`