Question

A heavy boy and a lightweight girl are balanced on a massless seesaw. The boy moves backward, increasing his distance from the pivot point. What happens to the seesaw? It is impossible to predict without knowing additional information. The side the boy is sitting on will tilt downward. The side the girl is sitting on will tilt downward. Nothing; the seesaw will remain balanced.

Answer 1

Answer:

The side the boy is sitting on will tilt downward.

Explanation:

According to the law of moments when the same force is applied at a greater distance from the pivot then the effect of moment is greater about that point.

Mathematically momentum is given as:

$M=F\times r$

where:

F is the applied force at a distance 'r' acting in a direction perpendicular to the line joining the point of application and the hinge.

• Moment is the rotational effect of the applied force on the body.

When the boy of a heavier mass than the girl was sitting on a balanced see-saw then it is certain that he was closer to the hinge than the girl to balance the turning effect (in case of an unbiased see-saw). When the body moves farther his weight is same but the radial distance from the hinge increases which increases his moment of weight.