Question

9.
Pushing force making an angle o to the horizontal is applied on a block of weight W placed on a
horizontal table. If the angle of friction is phi, the magnitude of force required to move the body is
equal to:
(A) W cos phi/cos (theta - phi)
(B) W sin phi/ cos (theta + phi)
(C) W tan phi/sin (theta - phi)
(D) W sin phi/ tan (theta - phi)​

Answer 1

Answer:

B

Explanation:

N=W+Fsinθ

∴f max=μN=(tanϕ)(W+Fsinθ)

To move the body;

Fcosθ=f max=(tanϕ)(W+Fsinθ)

Solving this equation we get,

f= Wsinϕ/cos(θ+ϕ)