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A solid cylinder with diameter 20cm has an angular velocity of 10m/s and angular momentum of 2kgm^2/s. What is its mass?

User Wrbp
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1 Answer

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Hi there!

Recall the equation for angular momentum:

L = I\omega

L = Angular momentum (kgm²/s)
I = Moment of Inertia (kgm²)
ω = angular velocity (rad/s)

We know that the Moment of Inertia of a solid cylinder is equivalent to:

I = (1)/(2)MR^2

M = mass (kg)
R = radius (m)

Plug in the givens to solve for the moment of inertia. Remember to divide the diameter by 2 for the radius, and to convert to meters.


r = (d)/(2) = 20/2 = 10 cm \\\\10 cm = 0.1 m


I = (1)/(2)M(0.1^2) = 0.005 M

We can rearrange the equation of angular momentum to solve for mass.


L = 0.005M * \omega\\\\(L)/(0.005 \omega) = M \\\\M = (2)/(0.005(10)) = \boxed{ 40 kg}

User UDalillu
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