Analyzing Inelastic Collision Data from a graph

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Homework Help Overview

The discussion revolves around analyzing data from a force versus displacement graph related to a head-on inelastic collision between two masses. Participants are tasked with completing a data table and finding the positions of the two masses post-collision.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants attempt to apply impulse and momentum formulas to the graph but express confusion over specific values derived from the graph. Questions arise regarding the interpretation of the graph, particularly which parts correspond to the forces on each mass. There is also discussion about the relationship between force, displacement, work, and energy.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the graph and questioning the assumptions made about the forces involved in the collision. Some guidance has been offered regarding the relationship between impulse and the area under the force versus time graph, but there is no consensus on how to proceed with the analysis.

Contextual Notes

Participants note that the problem is framed within the context of algebraic physics rather than calculus, and there is uncertainty about the definitions of certain variables, such as displacement and time, as well as the implications of the inelastic nature of the collision.

elements
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Homework Statement



A head on collision between mass and mass B occurs as described in the F vs s graph below.

Complete the table in the data section

Find [itex]\vec{x}[/itex]A
Find [itex]\vec{x}[/itex]B

see attached page for clarification

Homework Equations


P=m*v
[itex]\Delta[/itex]P=F*t
Ek=[itex]\stackrel{1}{2}[/itex]mv2
[itex]\vec{d}[/itex] = [itex]\vec{v}[/itex]t
W=F*[itex]\vec{d}[/itex]

The Attempt at a Solution



I've attempted to use the impulse and the momentum formula to apply to the graph but the numbers just isn't matching up I am unsure of how the 0 and 75 was arrived at just by observing the graph nor can I figure out how velocity 1 was 24 vs v2 at 0.

This is algebraic physics not calculus.
 

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elements said:

Homework Statement



A head on collision between mass and mass B occurs as described in the F vs s graph below.

Complete the table in the data section

Find [itex]\vec{x}[/itex]A
Find [itex]\vec{x}[/itex]B

see attached page for clarification

Homework Equations


P=mv
[itex]\Delta[/itex]P=Ft



The Attempt at a Solution



I've attempted to use the impulse and the momentum formula to apply to the graph but the numbers just isn't matching up I am unsure of how the 0 and 75 was arrived at just by observing the graph nor can I figure out how velocity 1 was 24 vs v2 at 0.

This is algebraic physics not calculus.
I don't quite understand your graph. There are two forces: the force on A and the force on B. There is one line joining several data points (F, s). Which parts of the graph relate to the force on A and which relate to the force on B?

AM
 
The impulse is the area under the F vs t graph.
You graph is F vs s (is s displacement?) ... what equations have force and displacement together?

Physics without calculus??!
Oh and I see the "lab" did not involve any actual practical work.

It looks a bit like sudoku: you can't just fill it in left to right. The force-displacement graph can be used to tell you the work, and so the change in energy. You need the relations between work, energy, and force, and displacement to understand it.

The graph looks like the force-displacement for one object from the point of contact.
It approaches the target under acceleration of 8N force pointing the other way, comes to rest, then bounces off.
The force during the recoil is less than during the approach.
Is this correct?

These look to be pretty big objects though.
 
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Simon Bridge said:
The impulse is the area under the F vs t graph.
You graph is F vs s (is s displacement?) ... what equations have force and displacement together?

Physics without calculus??!
Oh and I see the "lab" did not involve any actual practical work.

It looks a bit like sudoku: you can't just fill it in left to right. The force-displacement graph can be used to tell you the work, and so the change in energy. You need the relations between work, energy, and force, and displacement to understand it.

The graph looks like the force-displacement for one object from the point of contact.
It approaches the target under acceleration of 8N force pointing the other way, comes to rest, then bounces off.
The force during the recoil is less than during the approach.
Is this correct?

These look to be pretty big objects though.

Well this is a collision type problem, which means conservation of momentum occurs, so I'd assume you are correct but I'm not so sure, myself. I mean I have the impulse and Kinetic energy recorded per area of contact with the force turning points. But I am not sure how to factor in the time thing or what xa means, I'm assuming it's displacement of object A and object B but I have no clue how to find that out from the graph or the data given. especially with time involved, I don't know where 1s is or where 0s was.

Andrew Mason said:
I don't quite understand your graph. There are two forces: the force on A and the force on B. There is one line joining several data points (F, s). Which parts of the graph relate to the force on A and which relate to the force on B?

AM

I do not know which relates to which, what I do know is that this is a inelastic collision so I am assuming that that is the total force/displacement of the two objects together.
 
Last edited:
elements said:
I do not know which relates to which, what I do know is that this is a inelastic collision so I am assuming that that is the total force/displacement of the two objects together.
? The motion of the centre of mass of the two objects cannot change if the only forces are due to the collision. So if the graph is supposed to represent the force on the two bodies stuck together after the collision, the force should be 0.

Can you give us the whole problem as it was presented to you, before you wrote anything on the graph? Can you then give us all the data that you have and tell us where it comes from?

AM
 

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