A rectangular plank with mass m kilograms measures x metres
wide by y metres high. It is clamped at its very left edge, one
third of the way down from the top, as shown. To keep the
plank level, the clamp must exert a torque of
wide by y metres high. It is clamped at its very left edge, one
third of the way down from the top, as shown. To keep the
plank level, the clamp must exert a torque of