In the arrangements shown, the pulley is smooth and the rope is inextensible. If the system is in equilibrium, the contact force between ground and block is

Options

A. `30 N`
B. `40 N`
C. `50 N`
D. `60 N`

Answer

C

Explanation

`rArr N + 30 sqrt2 sin 45^(@) = mg`
`30 sqrt2 cos 45^(@) = f`
`N = 70 - 30 " " f = 30 N`
`= 40 N`
Reaction force `= sqrt(N^(2) + f^(2)) = 50 N`