A block placed on a horizontal surface is being pushed by a forceF making an angle 0 with the verticle If the friction coefficient is mu how much force is needed to get the block just started Discuss the situation when tantheta lt mu.

A block placed on a horizontal surface is being pushed by a forceF mak

1.	A block placed on a horizontal surface is being pushed by a forceF making an angle 0 with the verticle If the friction coefficient is mu how much force is needed to get the block just started Discuss the situation when tantheta lt mu.
Answer» Solution :In limitting equilibrium force of friction `F = mu R` In equilibrium ALONG the HORIZONTAL `F SIN theta = mu R` and along the verticle `F cos theta + mg = R = (F sin theta )/(mu` `:. Mg = F(( sin theta )/(mu) - cos theta)` or `F = (mu mg)/(sin theta - mu cos theta)` If tan `theta lt mu` `(sin theta - mu cos theta lt theta)` `:. F` is negative So for angles less angles less than `tan^(-1) mu` on cannot push the BLOCK ahed howsoever large the force may be .