An input force of 20 newtons is applied to a lever at a distance of 2 meters from the fulcrum. An object 0.5 m away from the fulcrum (and on the other side) is lifted by the 20-N force. What is the output force?

Question

690 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-02-12T04:24:48

80 Newtons

The number that will be the same for both the input and the output is the force times the distance. This is the basic principle of torque.

Therefore, we can calculate this two identical ways: proportionally or directly.

Proportionally, the "lever arm" has split into four, therefore the force must quadruple.

Directly calculating,

#tau = F_1 l_1 = F_2 l_2 #

#F_2 = (F_1 l_1)/l_2#

#F_2 = (20\ N cdot 2\ m)/(0.5\ m) = 80\ N#