(adsbygoogle = window.adsbygoogle || []).push({}); Determining the work done on the puck using conservation of angular momentum?? Help!

This is what I did...

1) Given

m_{puck}= 0.300 kg

r_{initial}= 0.4 m

v_{initial}= 0.6 m/s

m_{puck}= 0.300 kg

r_{final}= 0.15 m

v_{final}= ____ m/s

ƩW = KE_{final}- KE_{initial}

2) KE_{initial}= (1/2)mv^{2}

KE_{initial}= (1/2)(0.300)(0.6^{2})

KE_{initial}= 0.054 J

3) KE_{initial}= (1/2)mv^{2}

KE_{initial}= (1/2)(0.300)v^{2}

KE_{initial}= 0.15v^{2}

4) Find v - Angular momentum is conserved due to a lack of friction. The puck goes from 40 cm to 15 cm, so it has a different angular momentum.

L_{initial}= L_{final}

Iω_{initial}= Iω_{final}

[STRIKE](0.300)[/STRIKE](0.4)(0.6)^{2}= [STRIKE](0.300)[/STRIKE](0.15)v^{2}

(0.4)(0.6)^{2}= (0.15)v^{2}

0.144/0.15 = v^{2}

0.96 = v^{2}

0.979 = v

5) Plug v back into Net work equation

ƩW = KE_{final}- KE_{initial}

ƩW = (0.979) - (0.054)

ƩW = 0.925 J

Which is wrong...

:(

Help!

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# Homework Help: Determining the work done on the puck using conservation of angular momentum? Help!

**Physics Forums | Science Articles, Homework Help, Discussion**