A student is making a model crane for an investigation. She makes two component models. Model 1 is of the caterpillar track base (how it's going to move), and Model 2 is of the hydraulic arm. (a) A cross-section view of one of the two caterpillar tracks used in the model is given in Figure 2. It is comprised of 2 wheels, each of radius 3 cm. The distance between the centres of the wheels is 20 cm. The caterpillar track is represented as a solid line in Figure 2, that is the straight line from A to B, the outer semicircle from B to C, the straight line from C to D and outer semicircle from D to A