(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 10.0g bullet is fired horizontally into a 106 g wooden block that is initially at rest on a frictionless horizontal surface and connected to a spring of constant 155 N/m. If the bullet-block system compresses the spring by a maximum of 78.0 cm, what was the velocity of the bullet at impact with the block?

2. Relevant equations

p=mv

where p is momentum, m is mass (kg), and v is velocity (m/s)

(1/2 m1 v1^2 + 1/2 m2 v2^2)initial = (1/2 m1 v1^2 + 1/2 m2 v2^2)final + 1/2kx^2

Where m is mass (kg), v is velocity (m/s), k is the spring constant (N/m), and x is the distance of compression (meters).

(1/2 m1 v1^2 + 1/2 m2 v2^2)initial = (1/2m3 v3^2)final + 1/2kx^2

Where m is mass (kg), v is velocity (m/s), k is the spring constant (N/m), x is the distance of compression (meters), m3 is the sum of the masses, and v3 is the combined, new velocity. Not even sure if this one makes sense, I kind of combined some equations.

3. The attempt at a solution

To sum up my attempt, I plugged all of my variables into my "combined" equation. Thus I had two variables, v1 and v3^2. I decided to make everything equal to v1 and plug that equation into the original "combined" equation. (I can't really copy that onto here because it had a gigantic square root symbol.) So then I solved for v3 and got a ridiculously low answer, 1.0217m/s. According to my text book, which has the same problem with different variables, the answer is 237m/s.

Can someone help me out? Also, is this considered a perfectly inelastic collision?

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# Homework Help: A Linear Momentum Problem

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