Is the Conservation of Energy Solution Correct?

AI Thread Summary
The discussion revolves around the application of the conservation of energy principle in a physics problem involving frictionless surfaces and a spring. The calculations show that the initial and final energy states are equated, leading to the determination of velocities at different points. The frictional force between points B and C is accounted for, allowing for the calculation of the coefficient of kinetic friction. The computations appear correct, and the final value for the coefficient of friction is deemed reasonable. Overall, the approach to solving the problem using energy conservation is validated.
Ammar w
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Homework Statement



Here's the problem :

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

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:
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I haven't double checked each computation, but your method is correct and the final answer is reasonable.
 
LastOneStanding, Thank you.
 

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