A mass of 1.2 kg is located at the end of a very light and rigid rod 50 cm in length...?

Question

A mass of 1.2 kg is located at the end of a very light and rigid rod 50 cm in length. The rod is rotating about an axis at its opposite end with a rotational velocity of 4 rad/s.

(a) What is the rotational inertia of the system?
______ kg·m2
(b) What is the angular momentum of the system?
_____ kg·m2/s

Answer 1

First calculate I

for the rod I=m*L^2/3
although it seems the rod mass is negligible


for the point mass
m*r^2
1.2*.5^2
0.30 kg m^2

angular momentum is
0.30*4
1.2 kg m^2/s

j

Answer 2

a) I = m*L² = 1.2*.5² kg∙m²

b) L = I*ω = I*4 kg∙m²/s