The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

Conservation of Momentum?

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.
(edited 9 years ago)
Reply 1
Avatar for aoxa
aoxa
11
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 :smile:
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 :smile:


Yeah but I want to know if this can happen in different directions perpendicular to each other?
Reply 3
Avatar for lerjj
lerjj
13
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?
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.
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
Reply 6
Avatar for lerjj
lerjj
13
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.
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.


Thank-you, I had completely forgotten about the particles/rotational effects thing.
And the units of momentum are Ns, as it's kgms-1 which could also be kgms-2*s which is equal to Ns.
Reply 8
Avatar for lerjj
lerjj
13
Original post by womanofsteel
Thank-you, I had completely forgotten about the particles/rotational effects thing.
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.
Thank-you :smile:

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

the rotational thing seems most likely I'd guess.

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you