Final answer:
The new rotation rate of the merry-go-round after the children jump on, causing a 25% increase in the moment of inertia, is calculated using the conservation of angular momentum and is found to be 3.2 rev/min.
Step-by-step explanation:
The question addresses the concept of angular momentum and its conservation in the context of a merry-go-round. The conservation of angular momentum dictates that the product of the moment of inertia and the rotational speed (angular velocity) is constant for a closed system with no external torques.
Given that a merry-go-round is initially rotating at 4.0 rev/min and its moment of inertia increases by 25% due to three children jumping on it, we can determine the new rotation rate using the following steps:
Let I represent the initial moment of inertia of the merry-go-round and ω be the initial rotation rate (4.0 rev/min).
The conservation of angular momentum before and after the children jump on can be written as
I * ω = (I + 0.25I) * ω’, where ω’ is the new rotation rate.
Solving for ω’, we find that ω’ = (I * ω) / (1.25I) = ω/1.25.
Plugging in the initial rotation rate (4.0 rev/min), we get ω’ = 4.0 rev/min / 1.25 = 3.2 rev/min.
The new rotation rate of the merry-go-round after the children jump on is 3.2 rev/min.