A boy has a mass 40kg and a girl of mass 30kg play on a see-saw, where must the girl sit to make it balance?
if boy at 1 meter
girl at (4/3) meter
To determine where the girl must sit on the see-saw to make it balance, we need to consider the principle of moments or torques. The principle states that for an object to be in rotational equilibrium, the sum of the clockwise moments must be equal to the sum of the counterclockwise moments.
In this scenario, the moment depends on two factors: the mass of each individual and their respective distances from the pivot point. Let's assume the pivot point as the center of the see-saw.
Let's denote the boy's mass as m1 (40 kg) and the girl's mass as m2 (30 kg). Let the distance of the boy from the pivot be d1, and the distance of the girl from the pivot be d2.
To balance the see-saw, the total moment on one side (boy's side) must be equal to the total moment on the other side (girl's side). Mathematically, this can be represented as:
m1 * d1 = m2 * d2
Substituting the given values, we have:
(40 kg) * d1 = (30 kg) * d2
To solve for the unknown, we rearrange the equation:
d2 = (40 kg * d1) / 30 kg
This equation tells us the distance the girl should sit from the pivot point to balance the see-saw, given the boy's distance.