Q. A crane of weight W has a length (wheelbase) c, and its center of mass is midway between the wheels (i.e., the mass of the lifting arm is negligible). The arm extending from the front of the crane has a length a and makes an angle theta with the horizontal. The crane contacts the ground only at its front and rear tires. Given the angle theta_min, what is the highest weight (or load) W_L,max that this crane can lift without tipping forward? (Recall that weight has units of force.)

Express the highest load in terms of theta_min and other quantities given in the problem introduction.