The device shown is a pointer that mounts on the front of a tractor to help its operator p...

The device shown is a pointer that mounts on the front of a tractor to help its operator position the tractor relative to other rows of seeds that have been planted. Bracket E is bolted to the front of the tractor, which drives in the z direction. The bracket supports the bent boom A B C, the end C of which has a weight W and a pointer CD. The boom is allowed to rotate about line a, which lies in the yz plane, so that if the boom strikes an obstruction, the boom will rotate backward and upward to help avoid damage to it. If W = 501b, determine the force F, which acts in the −z direction, that will cause the boom to begin rotating about line a.

Figure P4.83