Impulse-Change in Momentum Lab

In summary, the conversation discusses a student's confusion with their data in an impulse-change in momentum lab. They provide their data table and explain how they calculated momentum and change in momentum. They also mention that the lab handout suggests a linear relationship, but the graph does not show one. The conversation includes attempts at finding a solution and additional information about the setup and measurement methods used in the lab. Ultimately, the student is unsure if their data is incorrect or if there is a problem with their calculations.
  • #1
Animal
16
0

Homework Statement


Im doing an impulse-change in momentum lab, and somethings not adding up. My data is as follows:

Trial Vmin Vmax Mass Impulse
1 -.6447 .5766 .548 .9952
2 -.9044 .7803 .598 2.281
3 -.9416 .8343 .548 1.597
4 -.5553 .4425 .598 1.246
5 -1.054 .9313 .498 .9239
6 -.4706 .3409 .498 .3408

Then I figured Momentum by multiplying each Vmin and Vmax by its respective mass, then found the change in momentum by subtracting each Pmin from its respective Pmax. So the final data table looks like this:

Trial Change in Momentum Impulse
1 .6692 .9952
2 1.0074 2.281
3 .9732 1.597
4 .5966 1.246
5 .9886 .9239
6 .4041 .3408

The lab handout tells me that there should be some sort of linear relationship here, but when I graph it there's no rhyme or reason, let alone anything linear. Anyone know what I've done wrong?

Homework Equations


none, really, except that Momentum=m*v
Impulse was found with the computer program that we collected the data with

The Attempt at a Solution


its up there in part one, kind of integrated with everything else. sorry about the lack of organization
 
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  • #2
Allright, I ran a best-fit line anyway and got a slope of 1.9 and a y intercept of -.23

The slope is supposed to be 1 and the y-int is supposed to be 0, since impulse=change in momentum. I would understand if there were a small error, but 1.9 is way off.

I switched axises (axes?) and got a slope of .277 and a y-int of .432.

Any ideas?
 
  • #3
It would help if you told us what you did in the experiment. What was moving? What are the min and max velocities in your table? What produced the impulse and how was it measured?
 
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  • #4
OlderDan said:
It would help if you told us what you did in the experiment. What was moving? What are the min and max velocities in your table? What produced the impulse and how was it measured?

Sorry, it was a cart and track setup.


|force sensor|--elastic-cord-----o|cart|o <[motion detector]

We used a Vernier LabPro, and we found Impulse with the computer by finding the area under the curve on the graph.

we pushed the cart away from the force sensor and it rebounded.
 
  • #5
is my data just really off, or is there some calculation problem that I'm making?
 
  • #6
Animal said:
is my data just really off, or is there some calculation problem that I'm making?

So vmin and vmax are velocities before and after the elastic has turned the cart, and hopefully the times at which those data were recorded correspond to the ends of the interval you used to calculate the impulse. I don't know how you matched up the times of velocity measurement with your force curves, but that is a potential source of error. You appear to have computed your momentum changes correctly, so I guess your data is very scattered. Fitting the curve to a line is the bast you can do.

It would be appropriate in this case to do a fit that forces the line through the origin, since you expect zero change in momentum to correspond to zero impulse. I'm not sure if your calculator or computer program gives you that option, but if your fitted curve is far from the origin and you have the option to force it to the origin you probably want to use it.
 

1. What is the purpose of an Impulse-Change in Momentum Lab?

The purpose of an Impulse-Change in Momentum Lab is to investigate the relationship between impulse and change in momentum. This lab allows scientists to explore the concept of impulse and how it affects an object's momentum.

2. How is impulse calculated in this lab?

In this lab, impulse is calculated by multiplying the force applied to an object by the time interval in which the force was applied. This can be represented by the equation I = FΔt, where I is impulse, F is force, and Δt is the change in time.

3. What is the significance of understanding impulse and change in momentum?

Understanding impulse and change in momentum is crucial in understanding how objects move and interact with each other. It allows scientists to predict and analyze the motion of objects, and it is also important in fields such as engineering and sports.

4. How is the data collected and analyzed in an Impulse-Change in Momentum Lab?

In this lab, data is collected by using a force sensor to measure the force applied to an object and a motion sensor to measure the change in momentum of the object. The data is then analyzed by plotting a graph of force versus time, and calculating the area under the curve to determine the impulse.

5. What are some potential sources of error in an Impulse-Change in Momentum Lab?

Some potential sources of error in this lab include human error in recording data, friction or air resistance affecting the motion of the object, and the accuracy of the force and motion sensors. It is important to take multiple trials and average the data to reduce the impact of these errors.

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