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Simple harmonic motion and amplitude

  • Thread starter Dotty21690
  • Start date
  • #1
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Homework Statement



A 2.10-kg block is suspended from a spring with a spring constant of 280.0 N/m. A 0.070-kg bullet is fired into the block from directly below with a speed of 220.0 m/s and is embedded in the block. Find the amplitude of the subsequent motion.

-What fraction of the original kinetic energy of the bullet appears as mechanical energy in the system of block-spring-bullet?

Homework Equations



we are learning about the oscillations and energy. For this question i'm thinking I would need to use E= Kinetic energy + potential energy.... (1/2)KA2=(1/2)mv2 + (1/2)Kx2
but I don't know what to do to get started, I am soo lost!

The Attempt at a Solution

 

Answers and Replies

  • #2
Doc Al
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Start by finding the speed of the "bullet + block" immediately after the bullet embeds itself in the block. What's conserved during that 'collision'?
 
  • #3
648
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I suggest using conservation of momentum on the collision between the bullet and block to find the initial velocity upwards of the block.
 
  • #4
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thanks! but then how would I find part b? would I find the kinetic energy of the bullet and the mechanical energy of the system(in which I would plug back in my value for the amplitude?)
 
  • #5
Doc Al
Mentor
44,882
1,129
thanks! but then how would I find part b? would I find the kinetic energy of the bullet and the mechanical energy of the system(in which I would plug back in my value for the amplitude?)
Compare the KE before and after the collision.
 

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