Calculating final rotational speed from angular velocity

[Anmol Dubey]

Homework Statement

An ice skater is spinning with a rotational speed of 1.5 rev/s. When he extends his arms and one leg, his rotational inertia increases by a factor of three. What is his final rotational speed?

Relevant Equations

Angular momentum is conserved
L = Iw
L (final) = L (initial)
I(initial)*w(initial) = I(final)*w(final)

I have no idea how to go about this. Any help would be appreciated thanks :)
Edit: I converted the 1.5 rev/s to rad/s = 9.4 rad/s

 

[Orodruin]

What do you know about the quantities in your last relevant equation?

 

[Anmol Dubey]

What do you know about the quantities in your last relevant equation?

Like I = mr²?
w = Δθ/Δt
I didn't get what you mean by quantities

 

[Orodruin]

Like I = mr²?
w = Δθ/Δt
I didn't get what you mean by quantities

No, what does the problem formulation tell you about these quantities:
I(final)
I(initial)
w(final)
w(initial)

 

[Anmol Dubey]

No, what does the problem formulation tell you about these quantities:
I(final)
I(initial)
w(final)
w(initial)

Since L is conserved
If I(final) is increased by a factor of 3, the w(final) is decreased by a factor of 3 so that L(final) = L(initial)
I(initial)*w(initial) = I(final)*w(final)
x*9.4 rad/s = 3x * w
so w(final) = 9.4 rad/s / 3
= 3.1 rad/s
Is that correct?

 

[Orodruin]

Is that correct?

Yes.

 

[Anmol Dubey]

Yes.

Thank you for helping