Question

Two children sit balanced on a seesaw with the pivot point located at the center of the seesaw. If the first kid has a mass of 36 kg and sits at a distance of 1.2 meters from the pivot, where should the second kid of mass 24 kg sit to balance the see-saw?

Answer 1

To solve the problem it is necessary to apply the concepts of Torque and equilibrium.

The Torque is defined as:

`\tau= F*d`

Where

F= Force

d = Distance

In this particular case, the force is caused by the weight of both children.

In turn, when there is equilibrium, the two torques must be equal therefore

`\tau_1 = \tau_2`

`m_1gd_1 = m_2_gd_2`

`m_1d_1 = m_2d_2`

Replacing with our values

`(36)(1.2)=(24)d_2`

Re-arrange to find
`d_2`

`d_2 = ((36)(1.2))/(24)`

`d_2 = 1.8m`

Therefore the distance that the second kid should sit to balance the see-saw is 1.8m from the pivot.