posted by Katie .
The mass of the tray itself is 0.182 kg, and its center of gravity is located at its geometrical center. On the tray is a 1.08 kg plate of food and a 0.279 kg cup of coffee. Assume L1 = 0.0590 m, L2 = 0.138 m, L3 = 0.258 m, L4 = 0.381 m and L5 = 0.401 m. Obtain the force T exerted by the thumb. This force acts perpendicular to the tray, which is being held parallel to the ground.
I've tried this and I don't understand anybody's work