Abdul is pushing his 20. kg little brother on a merry go round with a radius of 2.0m. if his little brother is on the edge of the merry go round and has a angular momentum of 360 kg m^2sec. what is his speed?

Angular momentum = inertia x rad/s = kg-m^2/s 

Inertia of little brother = mr^2 = 20 x 2^2 = 80 kg-m^2 

360 = 80 x rad/s 

360/80 = 4.5 rad/s (angular speed) probably the answer they are looking for. 

tangential speed = rad/s x radius = 4.5 x 2 = 9 m/s