2D Elastic Collision equations

AI Thread Summary
The discussion focuses on the equations governing 2D elastic collisions, emphasizing the principles of conservation of momentum and energy. Key equations are provided for momentum conservation in both the x and y directions, as well as the energy conservation equation, noting that for elastic collisions, kinetic energy loss (Q) is zero. The importance of understanding these principles is highlighted for solving collision problems effectively. Additionally, the user seeks resources for both 2D and 3D collision equations to aid in developing a collision simulation program. The mention of using Newton diagrams for geometric solutions to 2D collisions offers a practical approach to the topic.
vip4
Messages
4
Reaction score
0
Does anyone know the equations for 2D elastic collisions.
 
Physics news on Phys.org
Don't just learn the equations. Learn the principles behind those equations. You will always have conservation of momentum in any collision. For elastic collisions energy is also conserved. This will give you enough info the solve any collision problem, in principle anyway.
 
Conservation of momentum:

m_1 v_1 \cos \theta_1 + m_2 v_2 \cos \theta_2 = m_1 v_1^\prime \cos \theta_1^\prime + m_2 v_2^\prime \cos \theta_2^\prime

m_1 v_1 \sin \theta_1 + m_2 v_2 \sin \theta_2 = m_1 v_1^\prime \sin \theta_1^\prime + m_2 v_2^\prime \sin \theta_2^\prime

Conservation of energy:

\frac{1}{2} m_1 v_1^2 + \frac{1}{2} m_2 v_2^2 = \frac{1}{2} m_1 {v_1^\prime}^2 + \frac{1}{2} m_2 {v_2^\prime}^2 + Q

where Q is the amount of kinetic energy lost in the collision (to "heat" or whatever). For an elastic collision, Q = 0.
 
Thanks for the reply galileo and jtbell. I have done a little reading on conservation of momentum and energy. I also search the internet for the equations and the theories involved in collisions. However i could only find 1D equations.

I would appreciate it if you could point me to any information that could help me to better understand it. I would also like any information on 3D collisions as well. The reason I'm trying to get this information is to write a computer program that simulates collisions.
 
I remember a neat way to solve 2D collision problems geometrically. Google for Newton diagrams.
 
Hello everyone, Consider the problem in which a car is told to travel at 30 km/h for L kilometers and then at 60 km/h for another L kilometers. Next, you are asked to determine the average speed. My question is: although we know that the average speed in this case is the harmonic mean of the two speeds, is it also possible to state that the average speed over this 2L-kilometer stretch can be obtained as a weighted average of the two speeds? Best regards, DaTario
The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
Back
Top