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Simple Harmonic Motion

  • Thread starter suspenc3
  • Start date
402
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1. Homework Statement

http://www.physics.umd.edu/courses/Phys122/Noyes/HW/hw1.pdf (pg 3)

2. Homework Equations

Im guessing that E = K + U has something to do with it


3. The Attempt at a Solution

Not really sure where to start..I tried a few approaches but none of them got me anywheres E = 1/2mv^2 + 1/2 kx^2..but im missing too many things..

Any help?
 

Answers and Replies

225
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when the bullet colides, it sticks. This means that energy is not conserved but something else is.
 
225
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by the way, the fact that the clay sticks and that the collision is therefore perfectly inelastic is one of those "assumptions"
 
Last edited:
402
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conservation of linear momentum?
 
225
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yes. now you can use that in combination with energy.
 
402
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so I have [tex]\frac{mv +Mv_2}{m+M} = v_f[/tex] where [tex]Mv_2[/tex] is going to be 0 since it is at rest?

and [tex]E=1/2mv^2 + 1/2kx^2[/tex]

Do i let m = m+M? and will 1/2kx^2 be 0 since the block can be considered to be at point x=0?...set it to zero and solve for v?
 
225
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you actually dont need to use energy untill you are ready to find the amplitude. You already have enough information to find the velocity.
 
402
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So imediately after the collision, the spring has no effect on the velocity?
 
225
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that's correct. two ways to understand that
1) imediately after colision, spring is not compressed and therefore applies no force.

2) even if it were compressed, a force causes an acceleration which only changes velocity of some period of time.
 
402
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Solved it..Thanks for the help
 
225
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good job, np
 

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