Problem

The Force Needed to Move a Crate To move a crate of mass m across a rough floor, you push...

The Force Needed to Move a Crate To move a crate of mass m across a rough floor, you push down on it at an angle θ, as shown in Figure for the special case of θ = 21°. (a) Find the force necessary to start the crate moving as a function of θ, given that the coefficient of static friction between the crate and the floor is, µs. (b) Show that it is impossible to move the crate, no matter how great the force, if the coefficient of sta tic friction is greater than or equal to 1/tan θ.