Perfectly elastic collision problem with no given values

In summary: Here is the equation I used:In summary, the two curling stones had the same initial speed, but the final speed was different because the stone with the lower initial speed hit the stone with the higher initial speed head-on.
  • #1
Balsam
226
8

Homework Statement


A curling stone with initial speed vi1 collides head-on with a second, stationary stone of identical mass, m. Calculate the final speeds of the two curling stones.

Homework Equations


See attached picture

The Attempt at a Solution


I solved for vf1 as shown, but my answer was wrong. I got vi1-vf2=vf1, but the correct answer is vf1=0. What did I do wrong?
IMG_6163.jpg
 
Physics news on Phys.org
  • #2
Please type your equations here, as the rules require, rather than uploading a picture. I have a very difficult time seeing anything you wrote in step 3, which is where you went wrong. It looks like you butchered your algebra, but I can hardly read it.

However, in general, to approach this problem, use the conservation of energy and the conservation of momentum. You'll then have a system of two equations and can solve for the velocities.
 
  • #3
I second @RedDelicious ' remarks about postings, and note that BvU has said the same in another of your threads. Please bear in mind that although typing costs you a bit of time it will save time for the many people who read it.

For perfectly elastic collisions, it can save a lot of working to use a simple mass-independent result relating initial and final velocities. This relationship can be derived from the two conservation laws, but using it avoids the quadratics that come from conservation of energy.
Look up coefficient of restitution, and consider the case where it is 1.
 
  • #4
haruspex said:
I second @RedDelicious ' remarks about postings, and note that BvU has said the same in another of your threads. Please bear in mind that although typing costs you a bit of time it will save time for the many people who read it.

For perfectly elastic collisions, it can save a lot of working to use a simple mass-independent result relating initial and final velocities. This relationship can be derived from the two conservation laws, but using it avoids the quadratics that come from conservation of energy.
Look up coefficient of restitution, and consider the case where it is 1.
I just thought it would make more sense if I showed a picture of exactly what I did
 

What is a perfectly elastic collision?

A perfectly elastic collision is a type of collision in which the total kinetic energy of the system is conserved. In other words, the total energy before and after the collision is the same. This means that there is no loss of energy due to heat, sound, or deformation.

What is the difference between perfectly elastic and inelastic collisions?

In a perfectly elastic collision, the total kinetic energy of the system is conserved, while in an inelastic collision, some of the energy is lost due to heat, sound, or deformation. In an inelastic collision, the objects stick together after the collision, while in a perfectly elastic collision, the objects bounce off each other.

What are the equations used to solve a perfectly elastic collision problem with no given values?

The equations used to solve a perfectly elastic collision problem with no given values are the conservation of momentum equation and the conservation of kinetic energy equation. These equations can be used to find the final velocities of the objects involved in the collision.

Can a perfectly elastic collision occur in real life?

In theory, a perfectly elastic collision can occur in real life, but in reality, it is nearly impossible to achieve. This is because there will always be some energy lost due to factors such as friction and air resistance. However, some collisions, such as collisions between subatomic particles, can be considered perfectly elastic.

What are the limitations of solving a perfectly elastic collision problem with no given values?

The main limitation of solving a perfectly elastic collision problem with no given values is that it assumes an ideal scenario where there is no energy lost due to external factors. In reality, there will always be some energy lost, so the solutions obtained may not be entirely accurate. Additionally, if there are more than two objects involved in the collision, the problem becomes more complex and difficult to solve without given values.

Similar threads

  • Introductory Physics Homework Help
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
14
Views
10K
  • Introductory Physics Homework Help
Replies
20
Views
971
  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
21
Views
4K
  • Introductory Physics Homework Help
Replies
10
Views
858
  • Introductory Physics Homework Help
Replies
15
Views
3K
  • Introductory Physics Homework Help
Replies
15
Views
1K
  • Introductory Physics Homework Help
Replies
16
Views
2K
  • Introductory Physics Homework Help
Replies
12
Views
1K
Back
Top