Calculating Velocity and Momentum in Inelastic Collisions

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Homework Help Overview

The discussion revolves around calculating velocity and momentum in the context of an inelastic collision involving two putties and a spring. The problem involves concepts from mechanics, specifically energy conservation and momentum conservation.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants explore the relationship between potential energy stored in the spring and kinetic energy of the putty. They discuss using the spring constant and displacement to find the initial velocity of the first putty after leaving the spring. Questions arise regarding the conservation of momentum in the collision and the factors affecting the distance traveled by the putties.

Discussion Status

Some participants have provided guidance on applying energy conservation principles and momentum conservation. There is an acknowledgment of missing information regarding friction and its effects on the motion of the putties, leading to further exploration of the problem's constraints.

Contextual Notes

Participants note the absence of friction in the problem setup and question how it might influence the motion of the putties. Additionally, the initial displacement of the spring is clarified as a critical piece of information for solving the problem.

mwahx3
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Putty of mass 5 is compresses a spring with stiffness consonant 3. The spring is stretched and the putty has a completely inelastic collision with another putty of mass 15. How fast and how far do the putties travel?

I have no idea how to begin.

thanks,,
 
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me neither...
are you sure it didn't tell you the displacement of the spring, if it gave you that the problem would be solvable
 
oh, right sorry. i forgot to include that -- 'with a distance of 6'

thanks for pointing that out.
 
oh, in that case...
PE=1/2kx^2 for spring... where k is the stiffness constant and x is the displacement
the spring transfers all its PE to the first putty's KE, so now you want to do KE=1/2mv^2 solving for the velocity of the first putty after it leaves the spring...
then do conservation of momentum... mv before= mv after
*the mass and velocity before is just the mass and velocity of the first putty, the mass after is the mass of both together and the velocity after is the joint velocity which you are solving for...
uhhh, the distance I am not so sure about
you didn't mention any friction in the problem so I assumed there was none... what exactly makes them slow down?
 

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