Final answer:
On a balanced seesaw, a 20kg girl sits 3 m from the pivot point and the other girl sits 2 m from the pivot. The second girl weighs 30 kg.
Step-by-step explanation:
In order for a balanced seesaw, the torques acting on both sides of the pivot point must be equal. The torque is calculated by multiplying the mass by the distance from the pivot point.
Let's define the mass of the first girl as m1, the distance from the pivot point to m1 as r1, the mass of the second girl as m2, and the distance from the pivot point to m2 as r2.
Since the seesaw is balanced, the torques on both sides must be equal:
m1 * r1 = m2 * r2
We know that m1 = 20 kg, r1 = 3 m, m2 = ??, and r2 = 2 m. Solving the equation, we can find the mass of the second girl:
20 kg * 3 m = m2 * 2 m
m2 = (20 kg * 3 m) / 2 m = 30 kg
Therefore, the second girl weighs 30 kg.