Question

A 40 kg boy sits at 1.2 m from the fulcrum of the see-saw. Where should another boy of 30 kg sit on the other side of the see-saw in order to balance it?

Answer 1

To balance a see-saw, a 30 kg boy should sit 1.6 meters from the fulcrum to balance a 40 kg boy sitting 1.2 meters from the fulcrum, as the torques on both sides need to be equal.

Step-by-step explanation:

The question pertains to the concept of torques and balance on a see-saw or lever system, which is a fundamental topic in physics. When a see-saw is in equilibrium, the torques produced by the children on either side of the fulcrum must be equal. The torque is the product of the force exerted by each child (due to their weight) and the distance from the fulcrum. So for two children to balance each other, the following relationship must be satisfied:

Weight of first child x Distance of first child from fulcrum = Weight of second child x Distance of second child from fulcrum

In this case, for a 40 kg boy sitting 1.2 m from the fulcrum, and another boy weighing 30 kg, we use the formula:

40 kg x 1.2 m = 30 kg x Distance of second boy from the fulcrum

To find the distance of the second boy from the fulcrum, we divide the product of the first child's weight and distance by the weight of the second child:

Distance of second boy from the fulcrum = (40 kg x 1.2 m) / 30 kg = 1.6 m