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# Conservation of Momentum? watch

1. Is it possible for momentum to be lost in one direction (for example, y-direction) and then gained in another (x-direction)? Or must the momentum lost and gained be all in one direction?
And if it isn't possible for momentum to be lost in one direction and gained in another then what could the possible causes of this loss and gain be?
Thanks.
2. (Original post by womanofsteel)
Is it possible for momentum to be lost in one direction (for example, y-direction) and then gained in another (x-direction)? Or must the momentum lost and gained be all in one direction?

Thanks.

Conservation of momentum states that momentum before = momentum afterwards. So say momentum before = zero. That means after the event, the momentum must still must be zero. An example my teacher used to use was shooting a gun. The bullet has x momentum, which means the gun has to recoil with -x momentum in the opposite direction, so the momentum after the shot being fired is still zero. As the x's cancel out.

Hope this makes sense, and it hope it helps
3. (Original post by aoxa)
Conservation of momentum states that momentum before = momentum afterwards. So say momentum before = zero. That means after the event, the momentum must still must be zero. An example my teacher used to use was shooting a gun. The bullet has x momentum, which means the gun has to recoil with -x momentum in the opposite direction, so the momentum after the shot being fired is still zero. As the x's cancel out.

Hope this makes sense, and it hope it helps
Yeah but I want to know if this can happen in different directions perpendicular to each other?
4. (Original post by womanofsteel)
Yeah but I want to know if this can happen in different directions perpendicular to each other?
It can't if they're perpendicular. If you treat momentum as a vector, you could resolve it into all the components you like, but momentum needs to be conserved in the direction of each vector.

Do you have a specific case which you're thinking of?
5. (Original post by lerjj)
It can't if they're perpendicular. If you treat momentum as a vector, you could resolve it into all the components you like, but momentum needs to be conserved in the direction of each vector.

Do you have a specific case which you're thinking of?
Yeah, that's what I thought.

I did a collision experiment between two toy cars to investigate the conservation of momentum and I have to now write up my results. I have calculated the change in momentum in the x and y direction and there was a gain of 0.13Ns in the x direction and a loss of 0.17Ns in the y direction. As part of my write up, I have to say what caused these gains and losses in momentum.
6. (Original post by womanofsteel)
Yeah, that's what I thought.

I did a collision experiment between two toy cars to investigate the conservation of momentum and I have to now write up my results. I have calculated the change in momentum in the x and y direction and there was a gain of 0.13Ns in the x direction and a loss of 0.17Ns in the y direction. As part of my write up, I have to say what caused these gains and losses in momentum.
I didn't see your experiment, is it possible the toy cars steered between impact and your measurement of momentum
7. (Original post by womanofsteel)
Yeah, that's what I thought.

I did a collision experiment between two toy cars to investigate the conservation of momentum and I have to now write up my results. I have calculated the change in momentum in the x and y direction and there was a gain of 0.13Ns in the x direction and a loss of 0.17Ns in the y direction. As part of my write up, I have to say what caused these gains and losses in momentum.
How much is that change as a %? That might just be experimental error- also, momentum does not have units of N, it has units if Ns-1. The cars also are not particles, and rotational effects may have skewed your data slightly.
8. (Original post by lerjj)
How much is that change as a %? That might just be experimental error- also, momentum does not have units of N, it has units if Ns-1. The cars also are not particles, and rotational effects may have skewed your data slightly.
And the units of momentum are Ns, as it's kgms-1 which could also be kgms-2*s which is equal to Ns.
9. (Original post by womanofsteel)
And the units of momentum are Ns, as it's kgms-1 which could also be kgms-2*s which is equal to Ns.
sorry, had a mind blip on the units...

the rotational thing seems most likely I'd guess.
10. Thank-you

(Original post by lerjj)
sorry, had a mind blip on the units...

the rotational thing seems most likely I'd guess.

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