Determine the compression in the spring

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Homework Help Overview

The problem involves a collision between two gliders of equal mass, where one glider is initially moving at 3.0 m/s to the right and the other at 3.0 m/s to the left. The collision is cushioned by a spring with a specified spring constant, and the task is to determine the compression in the spring when one glider's velocity changes to 1.5 m/s.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the initial velocities of the gliders and question the interpretation of final velocities during the collision. There is an exploration of the conservation of momentum and energy principles, with some participants seeking clarification on the implications of identical masses and the timing of momentum changes.

Discussion Status

The discussion is ongoing, with participants providing insights into the nature of the collision and the role of time in momentum changes. Some guidance has been offered regarding the application of conservation laws, but multiple interpretations of the velocities and their implications are being explored.

Contextual Notes

There is a noted confusion regarding the initial and final velocities of the gliders, particularly in relation to the timing of the collision and the definitions of final velocities in elastic collisions. The problem context includes specific values for mass and spring constant, which may influence the discussion.

rrosa522
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Homework Statement


A 1.2 kg glider moving at 3.0 m/s right
undergoes an elastic head-on collision with a glider of equal mass moving at 3.0 m/s left . T​
he collision is cushioned by a spring with k=6.0*10^4 N/m. Determine the compression in the spring when the second glider is moving at 1.5m/s. Ans =1.6cm

Homework Equations


same mass therefore..
vf1= Vi2
vf2= Vi1

The Attempt at a Solution


I think I would be able to do this question if could understand it. Is the initial velocity of the second glider 3m/s or 1.5m/s?. I would really appreciate if someone can explain this question to me because I really don't know where to start.​
 
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Initially, before the collision, each mass is moving at 3.0 m/s.
 
The equations given refer to the exchanged velocities after the collision wen they are not again in contact with each other. The question has been asked about the state when they are still existing force on each other through the spring. At that instant apply energy and momentum conservation.
 
TSny said:
Initially, before the collision, each mass is moving at 3.0 m/s.
My teacher told me that when the masses are identical then vf1= Vi2 and vf2= Vi1, so how is it even possible that vf2=1.5m/s ?
 
Your teacher is right but does that happen in zero time just try to visualize the situation. Both change their momentum over a period of time called collision time. This time cannot be zero why. Why think it over. Suppose collision time is zero what will be the rate of change of momentum?
 
Let'sthink said:
Your teacher is right but does that happen in zero time just try to visualize the situation. Both change their momentum over a period of time called collision time. This time cannot be zero why. Why think it over. Suppose collision time is zero what will be the rate of change of momentum?
the momentum of both bodies wouldn't change if collision time was zero
 
It is given in the problem that the velocity of one has changed from 3.0 to 1.5. So what will be the velocity of the other as per conservation of momentum? Where has the KE of both gone?
 
rrosa522 said:
My teacher told me that when the masses are identical then vf1= Vi2 and vf2= Vi1, so how is it even possible that vf2=1.5m/s ?
That applies when 'final' refers to the completion of the collision process. It is clearly not true during the process. E.g., at some point they must both be instantaneously stationary.
 

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