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Help with momentum
curby
Registered User regular
Registered User regular
How does one go about calculating the velocity of 2 objects after they have collided?
For example, a 100kg car, travelling at 10m/s east, collides with a 200kg car, travelling at 20m/s west. What are the velocities of the 2 cars?
Edit: Or if they're both going west and the faster one collides into the slower one?
For example, a 100kg car, travelling at 10m/s east, collides with a 200kg car, travelling at 20m/s west. What are the velocities of the 2 cars?
Edit: Or if they're both going west and the faster one collides into the slower one?
curby on
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Sometimes after a collision, momentum is conserved. This is called an elastic collision. Which car ends up with how much momentum though is dependant on a number of factors. But if the collision is elastic, and you know how fast one car is travelling after the collision, you know the rest of the momentum is in the other car. Divide by mass to get velocity.
If the collision is inelastic, then it can be anything. A lot of the energy (momentum) is "used up" deforming the car and bending the metal etc. It can also disipate into sound etc. If a collision is inelastic, you will usually be given an "elasticity factor" for the collision, which is basically a measure of how much of the momentum is retained.
Actually, I just figured this out a few minutes ago.
This is an energy problem rather than a momentum problem.
If you take the initial 1/2mv^2 of both cars and make it equal to the final 1/2mv^2, the formula is easily dervied to get each velocity.
Kinetic energy is conserved in an elastic collision.