Calculating Vertical Momentum Conservation in a Collision

AI Thread Summary
The discussion revolves around a momentum conservation problem involving a bullet fired into a block of wood. The bullet, with a mass of 21.0g and a speed of 210 m/s, embeds itself in a 1.40-kg block at rest. The user calculated the momentum and the block's velocity post-collision but struggled to determine the height the block would rise. It was clarified that mechanical energy is conserved after the collision, and defining the coordinate system with the starting height as zero simplifies the problem. Ultimately, the user resolved the issue and indicated they would seek further assistance on a related topic in a new thread.
metalmagik
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Hello, I do not know how to do this momentum conservation problem in the vertical direction, when the object is to find how far the second object went.
A gun is fired vertically into a 1.40-kg block of wood at rest directly above it. If the bullet has a mass of 21.0g (.021 kg) and a speed of 210 m/s, how high will the block rise into the air after the bullet becomes embedded in it?
I have found momentum which was 44.1 kgm/s and the velocity of the block which was 3.15 m/s but I just do not know how I would find the distance the block traveled. The answer is .491 m. Quick help is appreciated, thank you.
 
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HINT: After the collision, mechanical energy is conserved.
 
I'm still a little confused, I've tried doing mgh = 1/2mv^2 + mgh but I realized I do not have the starting height...I am lost to what else I am supposed to do regarding this problem.
 
Just define your coordinate system so that the starting height of the block (i.e. the height of the table, or whatever it's on) is zero. Then when you solve for h that will be the height it reached off the table.
 
Thank you, I have solved this problem, it was really just a simple interpretation problem on my part, thanks again, I have one more question I do not quite understand that I expect to see on my exam tomorrow, I will post it in a new thread called "Momentum Particles" if anyone is kind enough to help me with it before the end of tonight.
 
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In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
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