# A girl 60kg stands at centre of a playground mery-g-round rotating about frictionles axle at 1 rad/s.treat m-g-round as a uniform disc(m=100kg radius=3m). If the girls jumps to a position 1m from the centre, what will be their angular v after she landed?

##### 1 Answer

The new angular velocity is

#### Explanation:

We need the initial angular momentum,

The girl will not count in the rotational inertia calculation because for her, radius is zero. So our m-g-r has initial rotational inertia

The formula for angular momentum is

When the girl jumps 1 m out from the center, she becomes an additional part of the rotational inertia.

The principle of conservation of momentum requires that the momentum after the jump is still

momentum before = momentum after

Solving for

I hope this helps,

Steve