Conclude Collision Experiment: Car Mass & K.E.

In summary, two cars with masses of 500g each collided, with car 2 initially at rest. After the collision, the cars stuck together and the kinetic energy was calculated to decrease from 0.233 to 0.125, resulting in a delta kinetic energy of 0.108. A conclusion was made that half of the initial energy was "wasted." A second experiment was conducted with car 1 having a mass of 700g, resulting in a delta kinetic energy of 0.112, leading to the assumption that delta energy is the same regardless of the weight of the cars. However, this generalization without considering uncertainty may not be accurate and further tests are needed. More discussion and calculations were done
  • #1
Drizzy
210
1

Homework Statement



Car 1 (500g) collides with car 2 (500g). The initial velocity of car 2 is 0. The cars stuck together after the collision.

I have to come to a conclusion about the results that i got.

Homework Equations



Kinetic energy before: 0,233

Kinetic energy after: 0,125

Delta kinetic energy: 0,108

The Attempt at a Solution



I also calculated delta Ek with an equation. (I will insert a picture)

So my conclution is that the energy that is "wasted" is half of the energy that we had in the biginning.

I did the same experiment but Car 1 had a mass of 700g and car 2 remained the same. delta kinetic energy was 0,112 which is almost the same as in the first one. So I guess that delta energy is the same no matter how much the cars wheigh. Is my assumption correct?

Should I add anything?
 

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  • #2
Drizzy said:
I did the same experiment but Car 1 had a mass of 700g and car 2 remained the same. delta kinetic energy was 0,112 which is almost the same as in the first one. So I guess that delta energy is the same no matter how much the cars wheigh. Is my assumption correct?

You have not stated your uncertainty at all. Such a generalization based on one experiment without uncertainty is unwarranted. Can you do some more tests?

To address your question: you can work out the energy loss during a completely elastic collision. Note that this depends on the frame of reference. If you analyze the collision from the center of mass frame you can work out the maximum energy loss.
 
  • #3
I'm sorry i didn't understand anything. I am not a native speaker. But no i cannot do more tests unfortunately. In my lab report i have written: "the lost energy is the same in both test but I need more tests to come to the conclusion that it remains the same even though the mass differs"
 
  • #4
Can anybody help me?
 
  • #5
Drizzy said:
So I guess that delta energy is the same no matter how much the cars wheigh. Is my assumption correct?
Calculate delta KE for the second experiment and see if it agrees with your data.
 
  • #6
I did. the first test was 0,108 and delta Ek on the second test was 0,112 so is it right?
 
  • #7
Drizzy said:
I did. the first test was 0,108 and delta Ek on the second test was 0,112 so is it right?
Can't say without more data. What was the initial KE for the second test?
 
  • #8
0.345
 
  • #9
And initial velocity of 700g car?
 
  • #10
0,962 was the initial velocity

it was a 753g car to be more specific
 
  • #11
And velocity of 735g and 200g cars after collision?
 
  • #12
Sorry i messed up the numbers...
This is test number 2:

Car 1
m = 0,753 kg
V0 = 0,962 m/s

Car 2 had the mass of 0,503 kg

Their total mass after the collision is 1,256kg

V1 = 0,613 m/s
V1 is their velocity after the collision
 
  • #13
What is the theoretical V1 (from conservation of momentum)?
 
  • #14
it should be 0,745

0,962^2 * 0,753/2 = v^2 * 1,256/2
 
  • #15
No. m1v1=m2v2
 
  • #16
right i forgot

it should be 0,5767
 
  • #17
With this V1, calculate theorectical final KE.
 
  • #18
it should be 0,209
 
  • #19
Right. And your experimental final KE?
 
  • #20
0,236
 
  • #21
Right. I would conclude that your experiment is not accurate enough to reach a conclusion on a pattern for delta KE.

You can now easily calculate delta KE for various masses and velocities and reach a theoretical conclusion.
 
  • #22
Thank you sosososososo much for helping me :)
 
  • #23
i did this on the first test and my theoretical final velocity should be 0,492 but Mine was 0,499

it is pretty close so what should i do with this one?
 
  • #24
Either redo it or discuss the problem with the result.
 
  • #25
i can't redo it :( my friend told me that they got delta Ek to 0,206 and 0,208 so I suppose that delta Ek should remain the same... but something was defintly wrong with my velocity because the momentum has to be the same but it wasnt
 
  • #26
Drizzy said:
i can't redo it :( my friend told me that they got delta Ek to 0,206 and 0,208 so I suppose that delta Ek should remain the same... but something was defintly wrong with my velocity because the momentum has to be the same but it wasnt
So your friend used different weights and velocities?
 
  • #27
yes
 
  • #28
Did your friend check the data and results against theory, like you did?
 
  • #29
He probably didn't :( I'll check with him tomorrow! It is past midnight :P I hope you are still able to help me tomorrow and thank you for everything
 

FAQ: Conclude Collision Experiment: Car Mass & K.E.

1. What is the purpose of the "Conclude Collision Experiment: Car Mass & K.E."?

The purpose of this experiment is to investigate the relationship between car mass and kinetic energy during a collision. This can help us understand the effects of different masses on the outcome of collisions and potentially improve car safety measures.

2. How is the experiment conducted?

The experiment involves setting up a track with a ramp at one end and a barrier at the other. A car of known mass is released from the top of the ramp and collides with the barrier. The car's velocity and deformation are measured to calculate its kinetic energy. The experiment is repeated with cars of different masses.

3. What is the expected outcome of the experiment?

We expect to see a direct relationship between the mass of the car and its kinetic energy. This means that as the mass of the car increases, its kinetic energy will also increase. This can be explained by the equation KE = 1/2 * m * v^2, where m is the mass of the car and v is its velocity.

4. How is the data analyzed in this experiment?

The data collected from the experiment is analyzed by plotting a graph of mass vs. kinetic energy. The slope of this graph represents the relationship between the two variables. Additionally, statistical analysis can be performed to determine the significance of the results.

5. What are the potential implications of the experiment's findings?

The findings of this experiment can have implications in the field of car safety. It can help inform car manufacturers on the importance of considering mass in designing safer vehicles. It can also be used to educate drivers on the potential impact of their car's mass on collisions and encourage them to drive more cautiously.

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