Answer:
Step-by-step explanation:
Conservation of angular momentum.
Disk I = ½MR²
Point mass I = mR² (boy)
Initial angular momentum
L₀ = Iω = ½MR²ω₀
Final angular momentum
L₁ = Iω = (½MR² + mR²)ω₁
as momentum is conserved, these are equal
(½MR² + mR²)ω₁ = ½MR²ω₀
ω₁ = ω₀(½MR²/ (½MR² + mR²))
ω₁ = ω₀(½M/ (½M + m))
ω₁ = 1.2(½(200)/ (½(200) + 50))
ω₁ = 1.2(⅔)
ω₁ = 0.8 cycles/second or 0.8(2π) = 1.6π rad/s