# Lever right shoulder 12cm, left arm 6cm. What force should act on the left arm

Lever right shoulder 12cm, left arm 6cm. What force should act on the left arm of the lever for balance if a force of 2 N acts on the right arm?

Given:

l1 = 12 centimeters – the length of the right arm of the lever;

l2 = 6 centimeters – the length of the left arm of the lever;

F1 = 2 Newton – the force that acts on the right arm of the lever.

It is required to determine F2 (Newton) – the force that must act on the left shoulder in order for the lever to be in balance.

We translate the units of measurement of length into the SI system:

l1 = 12 cm = 12/100 = 0.12 meters.

l2 = 6 cm = 6/100 = 0.06 meters.

Since the condition of the problem is not specified, we consider the lever itself to be weightless. Then, according to the leverage rule, we get:

F1 * l1 = F2 * l2;

F2 = F1 * l1 / l2;

F2 = 2 * 0.12 / 0.06 = 0.24 / 0.06 = 4 Newtons.

Answer: a force equal to 4 Newtons must act on the left arm of the lever.

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