The lever is acted upon by two forces, the shoulders of which are equal to 20 cm and 40 cm.

The lever is acted upon by two forces, the shoulders of which are equal to 20 cm and 40 cm. The force acting on the short arm is 6 N. What should be the force acting on the long arm for the lever to be in balance?

Given: l1 (length of the first arm of the lever) = 20 cm; l2 (length of the second arm of the lever) = 40 cm; F1 (force acting on the first (short) shoulder) = 6 N.
The acting force on the second (long) arm of the lever is determined by the formula (the rule of equilibrium of the lever): F1 / F2 = l2 / l1 and F2 = F1 * l1 / l2.
Calculation: F2 = 6 * 20/40 = 3 N.
Answer: The force acting on the long arm of the lever should be equal to 3 N.