Problem 31P

Calculate the moment of inertia of the array of point objects shown in Fig. 8–43 about (a) the vertical axis, and (b) the horizontal axis. Assume m = 1.8 kg, M = 3.1 kg, and the objects are wired together by very light, rigid pieces of wire. The array is rectangular and is split through the middle by the horizontal axis. (c) About which axis would it be harder to accelerate this array?

FIGURE 8–43

Solution:Step 1The young’s modulus is the ratio of longitudinal stress and longitudinal strain. FL Y = AeWhere, F is the force,L is the length,A is the cross sectional area,e is the elongation.