Question

How fast, in rpm, would a 130 g , 58-cm-diameter beach ball have to spin to have an angular momentum of 0.15 kg⋅m2/s ? Express your answer using two significant figures.

Answer 1

Mass of the ball =130 g

diameter of the ball = 58 cm

needed angular momentum = 0.15 Kg m ²/s

we know

where L is the angular momentum,

I is moment of inertia

is the angular frequency.

beach ball here can be considered as a spherical shell

for a spherical shell ,

is moment of inertia

is mass = 0.13 Kg

is radius = 0.29 m

give values we get

Kg m ²

from

Kg m ² /s

Kg m ²

give values

rad/s

which is 51  rpm

hope this helps , regards