A block placed on a horizontal surface i...

A block placed on a horizontal surface is being pushed by a force F making an angle `theta` with the vertical. If the friction coefficient is `mu`. How much force is needed to get the block just started.

`(mumg)/((sintheta-mucostheta))`

`((sintheta-mucostheta))/(mumg)`

`mumg`

none of these

Text Solution

Verified by Experts

The correct Answer is:

For vertical equilibrium of the block:
`R=Fcosb theta+mg` (i)
while for horizontal:
`Fsintheta=mur` (ii)
From (i) and (ii),
`Fsintheta=mu(Fcoshteta+mg)`
or `F=(mumg)/((sintheta-mucostheta))` .

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