A uniform bar of length L= 8 m, whose weight is 420 nt is placed into a totally frictionless, open top box in the shape of a cube whose sides are length s= 4m. Its bottom end is at a lower corner and it extends over the opposite top edge. See ATTACHMENT for a diagram with dimensions.
Find P, the force the top edge exerts against the bar.
The bar in equilibrium requires that 'net force=0' and also 'net torque=0 about any axis'. This solution is for an axis at the lower end of the bar.