Solving Momentum & Kinetic Energy Conservation: Lab Analysis

In summary, the conversation is about a lab on collisions and determining if momentum and kinetic energy are conserved. The person is asking for help on how to solve for kinetic energy and whether to solve it before or after. The expert advises to find the initial and final kinetic energy for each mass and compare them to see if they are equal. The person then asks for clarification on how to do this and the expert confirms that their method is correct. The person also mentions experimental error to consider when measuring velocities and masses.
  • #1
F.B
83
0
I just did a lab on collisions. We used a something like an air hockey table but different. Anyways i have to determine whether or not momentum and kinetic energy are conserved.

If there are no unknowns and you have the following information how would you determine if kinetic energy and momentum are conserved.

Mass 1 = 0.541 kg, Mass 2 = 0.541 kg, Vi 1 = 0.33 m/s, Vi 2 = 0, Vf 1 = 0, Vf 2 = 0.3 m/s.

All i need to know is if i should solve for Ekbefore first and then Ekafter or should i do Ekbefore=Ekafter that way all the masses and 1/2's cancel out. So which way is right.
 
Physics news on Phys.org
  • #2
I am not entirely sure about what you are trying to do (although my teacher will probably think i should be), but this looks like a fairly simple one to me. With simple question, the best thing to do usually is just starting to solve whatever you can. That should take less time than posting anything here.
 
  • #3
But i have no unknowns. I have to determine LS=RS sort of. But when i solve the left separately and the right side i get one answer but when i make both equations equal each other i get a different answer. Which is right?
 
  • #4
If this is a headon collision (no angle) then simply find the initial and final KE of each mass. If the total initial KE is equal to the total final KE then the KE is conserved. Same for momentum.
 
  • #5
so i do this.

Ekbefore=Ekafter
1/2m(1)Vi(1)^2 + 1/2m(2)Vi(2)^2 = 1/2m(1)Vf(1)^2 + 1/2m(2)Vf(2)^2
0.33^2=0.3^2
0.1089=0.09

There LS=RS sort of. Is that how you do it.
 
  • #6
Thats how you do it. That would mean that the KE isn't conserved. This is because that some of KE turns into heat energy during the collision and due to friction.
 
  • #7
How did you get the velocities? If velocitiy values, and the mass values for that matter, were measured, their should be some experimental error to consider.

Regards
 

1. What is momentum and how is it conserved?

Momentum is a measure of an object's motion, calculated by multiplying its mass by its velocity. According to the law of conservation of momentum, the total momentum in a closed system remains constant, meaning that the total momentum before an event must be equal to the total momentum after the event.

2. What is kinetic energy and how is it conserved?

Kinetic energy is the energy an object possesses due to its motion. It is calculated by multiplying half of the object's mass by its velocity squared. According to the law of conservation of energy, the total kinetic energy in a closed system remains constant, meaning that the total kinetic energy before an event must be equal to the total kinetic energy after the event.

3. How can the conservation laws of momentum and kinetic energy be applied in a laboratory setting?

In a laboratory setting, the conservation laws of momentum and kinetic energy can be applied by conducting experiments that involve the collision or interaction of objects. By measuring the masses and velocities of the objects before and after the event, the conservation laws can be used to analyze and predict the outcome of the event.

4. What factors can affect the conservation of momentum and kinetic energy?

There are several factors that can affect the conservation of momentum and kinetic energy, such as external forces acting on the system, friction, and the transfer of energy to other forms (such as sound or thermal energy). In addition, if the objects involved in the event are not isolated from their surroundings, the conservation laws may not hold true.

5. How can the results of a momentum and kinetic energy conservation lab analysis be applied to real-world situations?

The principles of momentum and kinetic energy conservation are applicable to various real-world situations, such as car crashes, sports collisions, and rocket launches. By understanding these laws and analyzing the data from experiments, scientists can make predictions and improve safety measures in these scenarios.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
363
  • Introductory Physics Homework Help
2
Replies
55
Views
1K
  • Introductory Physics Homework Help
Replies
6
Views
934
  • Introductory Physics Homework Help
Replies
1
Views
684
  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
612
Replies
1
Views
487
  • Introductory Physics Homework Help
Replies
7
Views
1K
  • Introductory Physics Homework Help
Replies
20
Views
1K
  • Introductory Physics Homework Help
Replies
10
Views
1K
Back
Top