Conservation of Momentum, Energy

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Homework Help Overview

The problem involves a bullet colliding with a wooden block, leading to the compression of a spring. It relates to the concepts of conservation of momentum and energy within the context of mechanics.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply conservation of momentum followed by energy conservation to determine the maximum compression of the spring. Some participants question the numerical calculations involved and suggest re-evaluating the inputs used in the equations.

Discussion Status

Participants are engaged in verifying the calculations and discussing the application of the relevant equations. There is an indication that the original poster has adjusted their approach based on feedback, leading to a refined answer.

Contextual Notes

There is mention of the original poster's struggle with numerical accuracy and the importance of precision in calculations. The problem setup includes specific values for mass, velocity, and spring constant, which are central to the discussion.

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Homework Statement



A bullet with mass 20 grams and velocity 100 m/s collides with a wooden block of mass 2 kg. The wooden block is initially at rest, and is connected to a spring with k = 800 N/m. The other end of the spring is attached to an immovable wall. What is the maximum compression of the spring?

Homework Equations



p=mv
K=.5mv^2
Spring potential energy = .5kx^2

The Attempt at a Solution



I tried doing M(bullet)V(initial) = [M(bullet) + M(block)][Vfinal], and then I used that final velocity in the energy equation .5mv^2 = .5kx^2 to find x. I keep getting the answer to be .49 meters, but this isn't correct.

What am I doing wrong?
Thanks!
 
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I think you have the concepts correct and are just doing the numbers wrong. With these inputs, 0.5mv^2~=1J = 0.5 kx^2, so x^2 ~= 1/400 m^2. How are you getting 0.49m?
 
Whoops, I mean I keep getting .049 meters.

But still, doing what you said isn't giving me the right answer!
 
Okay, I got it, never mind!

I was doing it correctly, I just didn't put in an exact enough answer!

It ended up being .0497!
 

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