Answer to Question #143744 in Physics for Zech

Question

A Flat bar is loaded with boxes. Box M = 50 kg, what must be the magnitude of mass m so that the bar becomes level? Neglect the weight of the bar. What torque about each end of the bar?

Answer 1

If the length of the bar is L, and its axis of rotation is at distance d from the point where mass M is attached, the value of mass m in order to balance M can be found from the equilibrium of torques:

$$Mgd=mg(L-d),\\\space\\ m=M\frac{d}{L-d}.$$

The torque about each end of the bar is

$$\tau_M=Md,\\ \tau_m=m(L-d).$$