Pushing force making an angle `theta` to the horizontal is applied on a block of weight W placed on a horizontal table . If the angle of friction is `phi` , magnitude of force required to move the body is equal to :

Options

A. `W "cos" phi //"cos" (theta-phi)`
B. `W "sin" phi //"cos" (theta+ phi)`
C. `W "tan" phi//"sin" (theta- phi)`
D. `W "sin" theta //
"g tan" (theta - phi)`

Answer

B

Explanation

F cos `theta = mu N`
F cos `theta = "tan" phi [omega + F "sin" theta]`
`F = ((omega "tan" phi)/("cos" theta - "sin" theta * "tan" phi))`