Conservation of Energy problem!

  • Thread starter Ammar w
  • Start date
  • #1
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Homework Statement



Here's the problem :

http://www.diigo.com/item/image/2sb3i/wonu [Broken]

Homework Equations



Ei = Ef

The Attempt at a Solution



The surface between A and B is frictionless :
Ei = Ef
KA + UA = KB + UB
mghA = 1/2 mvB2
vB2 = 2ghA = 2*9.8*3 = 58.8 m/s

The surface from C to the spring is frictionless :
Ei = Ef
1/2 mvC2 = 1/2 kx2
vC2 = kx2/m = 2250*0.32/10 = 20.25 m/s

The surface between B and C has a friction :
Ef - Ei = -fkd
1/2 mvC2 - 1/2 mvB2 = -ukmgd
1/2 m (vC2 - vB2) = -ukmgd
1/2 * 10 (20.25 - 58.8) = -uk*10*9.8*6
uk = 0.327

Right?
 
Last edited by a moderator:

Answers and Replies

  • #2
I haven't double checked each computation, but your method is correct and the final answer is reasonable.
 
  • #3
28
0
LastOneStanding, Thank you.
 

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