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# AQA Physics GCSE P2 & P3 [OFFICIAL THREAD] watch

1. (Original post by t.thompson22)
That's like the only thing in P2 which I can't get my head round either ������

Going to attempt it now, I hate the parachute thing too but need to go over it haha

I think it goes like this:

As soon as the skydiver jumps out the plane, the only force acting on him is his weight (gravity) so he accelerates, reaching higher speeds. Then, as the speed increases the air resistance begins to also, so the resultant force is less as although the weight force is still more than air resistance, it is less so than before so the skydiver still accelerates but at a slower rate. Then, as the forces of air resistance and weight reach equilibrium, the skydiver stops accelerating and travels at a steady speed (terminal velocity)

When the skydiver opens their parachute, suddenly the forces of air resistance are greater than the weight because of the increased surface area so the skydiver slows down. Because he slows down, the air resistance forces decrease, and reach equilibrium with the weight again but this time at a LOWER terminal velocity, so he can safely reach the ground
2. (Original post by Jules12345)
Haha like with a parachute? I just don't get it at all
Sorry forgot to quote you in this
I replied to it but it is later on, it won't let me quote you
3. (Original post by Jules12345)
I know! Hoping it won't cos wasn't it the six marker last year?
4. (Original post by isabellagrace)
Sorry forgot to quote you in this
I replied to it but it is later on, it won't let me quote you
Ah seen it thanks!!
5. Can anyone tell me what's predicted to come up for P2? And a 6 marker prediction too please?

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6. Good luck everyone today
7. (Original post by RotomGuy)
I revised all of Unit 3 in about a day, but most of Unit 2 still hasn't sunk in. Argh.
Same here :/ motions is the worst for me
8. (Original post by t.thompson22)
Good luck everyone today
Thanks and to you too

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9. (Original post by t.thompson22)
Ah so probs won't come up this year yhen
10. Today is the day
I'm just praying they won't be a momentum 6 marker (I doubt it though)
I can explain momentum and calculate basic momentum questions but that is all XD
11. (Original post by physicsamor)
Today is the day
I'm just praying they won't be a momentum 6 marker (I doubt it though)
I can explain momentum and calculate basic momentum questions but that is all XD
Can you please explain momentum to me!?
12. Can somebody please explain the motor effect to me? It's the only thing I'm stuck on.
13. (Original post by angellll)
Can somebody please explain the motor effect to me? It's the only thing I'm stuck on.
These videos may help:

https://goo.gl/zOvMVQ

14. Can you check if this is right?
The Electric Motor
1) A current is passed through the coil.
2) Each side of the coil experiences a force because of the motor effect (The magnetic field and the current causes there to be a force)
3) However, the two sides experience opposite forces due to the fact that current is travelling upwards on the first side of the coil and downwards on the second side of the coil but the magnetic field is the same.
4) Therefore, the coil starts to turn because one side has an upwards force and the other side has a downwards force.
5) Every half turn, the split-ring commutator reverses the current so that the coil turns in one direction.
15. (Original post by Jules12345)
Can you please explain momentum to me!?
Momentum is a vector quantity, which means it has a size and direction. All moving objects have momentum. This is therefore a measure of how hard it is to stop a moving object.

Momentum is conserved; momentum before = momentum after.
In a closed system (no external forces are acting) before an event such as a collision, is the same after the event. This is the conservation of momentum.
If momentum is not conserved it must mean that external forces were acting.

For example if you are jumping off a moving object with 0 momentum, the momentum after jumping would be 0 as momentum is conserved. What ever happens forward must happen backwards.

If two objects collide or intereact, the forces acting on them will be the same size but in opposite direction. This is the same for the change in momentum of each objects. This nmeans that basically the momentum lost by one of the objects will be gained by the other object. Therefore during a collision momentum is conserved (if no external forces act)
16. (Original post by harryleavey)
These videos may help:

https://goo.gl/zOvMVQ

Thank you so much!
17. Can you check if this is right please?
The Electric Motor
1) A current is passed through the coil.
2) Each side of the coil experiences a force because of the motor effect (The magnetic field and the current causes there to be a force)
3) However, the two sides experience opposite forces due to the fact that current is travelling in different directions through the two coils but the magnetic field is the same.
4) Therefore, the coil starts to turn because one side has an upwards force and the other side has a downwards force.
5) Every half turn, the split-ring commutator reverses the current so that the coil turns in one direction.
18. [QUOTE=angellll;56006667]Can you check if this is right please?
The Electric Motor
1) A current is passed through the coil.
2) Each side of the coil experiences a force because of the motor effect (The magnetic field and the current causes there to be a force)
3) However, the two sides experience opposite forces due to the fact that current is travelling in different directions through the two coils but the magnetic field is the same.
4) Therefore, the coil starts to turn because one side has an upwards force and the other side has a downwards force.
5) Every half turn, the split-ring commutator reverses the current so that the coil turns in one direction.[/QUOTE
Lalalal
19. (Original post by harryleavey)
These videos may help:

https://goo.gl/zOvMVQ

Sorry, have you got any of videos on transformers? X
20. (Original post by physicsamor)
Momentum is a vector quantity, which means it has a size and direction. All moving objects have momentum. This is therefore a measure of how hard it is to stop a moving object.

Momentum is conserved; momentum before = momentum after.
In a closed system (no external forces are acting) before an event such as a collision, is the same after the event. This is the conservation of momentum.
If momentum is not conserved it must mean that external forces were acting.

For example if you are jumping off a moving object with 0 momentum, the momentum after jumping would be 0 as momentum is conserved. What ever happens forward must happen backwards.

If two objects collide or intereact, the forces acting on them will be the same size but in opposite direction. This is the same for the change in momentum of each objects. This nmeans that basically the momentum lost by one of the objects will be gained by the other object. Therefore during a collision momentum is conserved (if no external forces act)
Thank you!

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