A boy of mass 55 kg runs on a line tangent to the edge of a merry-go-round,whose mass is 125 kg and radius 1.2 m.He jumps onto the merry-go-round,and the angular speed of the merry-go-round becomes 2.2 radians per second.How fast was the boy running before he landed on the merry-go-round?
A)5.6 m/s
B)6.8 m/s
C)8.6 m/s
D)3.2 m/s

Question

Quizplus · Accepted Answer

The conservation of angular momentum can be used here. The initial angular momentum of the boy is equal to the final angular momentum of the system (boy + merry-go-round). Using the formula: m*v*r = (I_merry-go-round + m*r^2)*ω, where I_merry-go-round = (1/2)*M*r^2, solve for v.

A Boy of Mass 55 Kg Runs on a Line