What is the angular velocity of the child and the merry-go-round?

[jk2455]

the statement:

a child runs at 3m/s and jumps tangentially onto a stationary merry-go-round. the moment of inertia of the merry-go-round is 360kgm² and the radius is 2.0m. what is the angular velocity of the child and the merry-go-round?

answer- 0.500rad s^-1 or 0.500s<sup>-1[/SUP

i honestly have no idea what to do could someone please break the question down to a bit easier understanding.</sup>

 

[eriadoc]

This is a conservation of momentum problem. Treat the child as a point mass on the rim of a circle to find the child's moment of inertia and then add it to the MGR to find total I.

 

[jk2455]

so this is what i did but now I am stuck and don't know if I am on the right track

I_child=45x2²
= 180kgm²
I_total=I_mgr+I_child
=540kgm²
V_f=m₁v₁+m₂v₂/(m₁+m₂)
=m₁v₁/(m₁+m₂)
=1 m/s