A uniform ladder is 10m long and weighs 400 N. It rests with itsupper end against a frictionless vertical wall. Its lower end rests on the ground and is preventedfrom slipping by a peg driven into the ground. The ladder makes a 30? angle with the horizontal.The magnitude of the force exerted on the peg by the ladder is:
A. zero
B. 200N
C. 400N
D. 470N
E. 670N