Question

A block of mass 2 kg is pushed against a rough vertical wall with a force os 40 N. Coefficient of static friction being 0.5. Another horizontal force is 15 N, is applied on the block in a direction paralle to the wall. Will the block move? If yes in which direction? If no, find the frictional force exerted by the wall on the block.

Answer 1

Normal reation on the block from the wall will be `(F_("net") =0`, perpendicular to the wall)

`R =F =20N`
Therefore, limiting friction `f_(1) =muR =((1)/(4)) (20) =5N`
Weight of the block is `w = mg =(1)(10) = 10N`
A horizontal force of `10N` is applied to the block. Both weight and this force along the wall the wall. The resultant of these two force will be `10sqrt2N` in the direction shown in figure. Since ,this resultant is greater than the limiting friction. The block willmove in the direction of `F_("net")`with acceleration.
`a =(F_("net")-f_(L)/(m) =(10 sqrt2-5)/(1) =9.14 m//s^(2))`