Help with Momentum.

[TheDamien]

I have some "cart" units that I'm moving along a single axis. They can have differing weights and speeds, but I have no idea how to calculate the transfer of momentum between colliding carts.

The track is frictionless.

Does anyone know a simple formula for figuring out the energy exchanged in a collision?

 

[vypur85]

m1v1 = m2v2

'm' could be the level of the unit...
'v' is the movement speed of the unit...

 

[TheDamien]

m1v1 = m2v2

'm' could be the level of the unit...
'v' is the movement speed of the unit...

I know how to calculate the momentum and I'm storing the mass and velocity in gamecache.

I'm looking for a way to calculate the energy exchanged in a collision between 2 carts.

Thanks anyway, but not quite what I'm looking for.

 

[MoonSlinger]

Newton's 2nd Law
Force = Mass x change in velocity
Newton's 3rd Law
Force applied = Force received.

Together:
Mass of Cart1 x velocity drop of Cart1 = Mass of Cart2 x velocity gain for 2nd cart

Next, you have to determine the type of impact:
Since Mass of Cart1 and Cart2 are predetermined, you have to "fix" one of the velocity change to find the other. Some examples of impact type as below:

- Cart1 or Cart2 stops after impact?
- Cart1 inherits the velocity of Cart2, while Cart2 moves off with a different velocity (or vice versa)

Above examples are there to "fix" one variable (change in velocity) so as to work out the other.

 

[vypur85]

Hmm.... Lemme give another try...

Since one cart A will knock another cart B, so cart B would have the kinetic energy from cart A. So if you wanna calculate the energy present in cart B now, maybe you can use the formula 0.5mv^2 (kinetic energy formula). Since momentum is MV, the formula can be rewritten as E = 0.5V (mv). Therefore, to calculate the energy experienced by cart B, jus multiply 0.5V to the current momentum of cart A (momentum of cart A and cart B should be the same, so you can find mv from cart A).

So,

m = weight of cart A
v = velocity of cart A before collision
V = velocity of cart B after collision

Is this what you wanted? Seems too physics to me = =. My initial reply was based on WE style of reply And i'm not sure whether my formula is correct or not (havent touched physics for 4 years). Hope what i'm crabbin makes sense in terms of WE world.....

PS: Your question seems like my exam paper question. Reminds me of those bad old days

 

[SaintMorose]

you need to consider whether you want them to
bounce, one to remain stationary, or both to stick together.

 

[Magentix]

Aren't single line movement forces also single line vectors?

Say F1 is a vector going leftwards with a force of 5N, representing the force that is created based on object 1's velocity(, acceleration) and mass.
Say F2 is a vector going rightwards with a force of 6N, representing the force that is created based on object 2's velocity(, acceleration) and mass.

The result would be that the point of collision experiences a movement of 1N rightwards, no?


I'm rusty on physics, but I believe it was something like that. :x

 

[vypur85]

you need to consider whether you want them to
bounce, one to remain stationary, or both to stick together.

Hmm.... Does it matter? I mean, m1v1 = m2v2.... The momentum will always be the same, right?

If it bounces: Means the knocking cart transffered part of its energy to the knocked cart while retaining some energy in itself.

If it doesnt bounce: Means the knocking cart transferred all its energy to the knocked cart. The knocking cart has zero velocity (so it does not have energy). Cart A will definately move (unless u glue it on the surface which is not likely as the surface is frictionless, as told by damien)

For both events above, the energy for knocked cart (cart B) can still be calculated because it will definately move thus has V2 (velocity after collision).


If both stick: They share the same energy (can be negative or positive energy depending on the direction they move after collision). Still, there is V2, so the energy after collision can still be calculated.....

So it doesnt really matter, right?

EDIT
Another event would be after collision, both move towards same direction but not sticking: Still has V2... So can E be calculated anyhow...