AQA Physics Unit 3 P3 GCSE 30th May 2012 Exam

1e) continous, dependent(1)

I bet you've done fantastically though! Not much I can do know about how I've done so I won't fret.

For the moment one, I subracted 2 from 8 to get the distance and then did (0.02*2)/6 to get the force which I got as 0.0067N... I wrote that total clockwise moments = total anti-clockwise moments...

How many marks do you think I will get?
Thanks!

I calculated as harshly as possible and got 30 out of 45, what would that be???

I thought it would be independent - time is what was being measured

What do you think 21 will be?

you seem to have done very well! a* definately based on that...But what is the actual answer to 5b?

i think i got 25-32 depending on the marksheme. i've gone past the point of caring about a A* now i need 65UMS for a A* overall, that is all i want, one way or another. Do you think i'll get it

How do aqa decide what exam papers are 'hard' therefore having low grade boundaries or 'easy'? Is it just based on the average score people get?

It was speed they were trying to measure. How the radius affects the speed, so radius is independent, time is dependent.

If someone can find a copy of the paper, I'm doing a degree in Physics, so I can give a unofficial mark scheme.

As a thanks for my work would you mark what i got please?

Right everyone here goes. It was sooo hard. So this is the answers i can remmeber and the questions i think it was.

UPDATED
I think these are in the right order

1a) Towards the centre of the circle (1)
1b) Tension in the rope (1)
1c) Because changing one of these would affect the centripetal force and the speed of the bung and they did it so that there was only one independent variable. For example, if the mass of the bung increased, the centripetal force needed to keep it moving at the same speed would need to be increased (2)
1d) So that their results were more reliable (1)
1e) continous, dependent(1)
1f) The bigger the centripetal force, the faster the speed needed to keep it moving in a circle (1)

2a) They suspended the card from a pole (the pole went through the hole) and the card came to rest with it's centre of mass directly below its point of suspension. It did this as its weight had had a turning effect that returned it to its equilibrium position. Then they drew a line vertically down using a plumbline. Then, the repeated the proccess from a different point on the card and drew another vertical line down when the object came to rest and the place where the lines meet is the centre of mass (3)
2b) they could test that the position is accurate by balancing the point where the lines cross on a pointed object like a sharp pencil. If the centre of mass is in the correct position it will balance, if it isn't, it won't (2)

3a) gravitational attraction between the satellite and the earth (1)
3b) No, because geostationary satellites orbit the earth once every 24 hours not twice every 24 hours. (2)

4a) This happens because of the motor effect. The wire moves upwards when the switch is closed because current flows through the circuit and a magentic field forms around the wire and this interacts with the magnetic field from the magnet and repulses it so it moves upwards (2)
4b) The motor effect (1)
4c) The wires direction of movement would be reversed five times every second (2)
4d) I cant remember this question but it was something to do with increasing the frequency. So here goes: The wire would move back and forth quicker and further (2)
4e)0.005 N (2)

5a) The maximum loudness of the notes are the same as they have the same mixmum amplitude (1)
5b) The first notes is a smooth sound whereas the second notes is a sharp, brassy sound (1)
5c) The amplitude (1)
5d) Because they can only hear sound including and above 48 decibels so they need people to talk louder than in a normal conversation because the normal conversation is 45 decibels (2)
5e) Crosses across twenty from 250-20000 Hz (1)
5f) Because it can damage their hearing (1)
5g)Because in the hall the sound will reflect of the walls meaning that the sound is louder (1)

6a) step up (1)
6b) because there are more turns on the secondary coil than on the primary coil (1)
6c)because it is a magnetic material (1)
6d) 60 turns (2)

7a) diverging lens (1)
7b) line from object through centre of lens. line focus thorugh the point where a line from the top of the object meets the vertical y axis. Arrow where they meet (3)
7c) 0.5 (2)
7d) because the image is formed on the same side of the lens as the object (1)

8a) the star runs out of hydrogen to fuse together in its core (1)
8b) The star expand, becomes hotter and then cools to form a red giant. It then contracts and cools even more to form a white dwarf. (3)

I think i got 32/45 i think i dropped 13

Here is what i think i dropped

1c) Because changing one of these would affect the centripetal force and the speed of the bung and they did it so that there was only one independent variable. For example, if the mass of the bung increased, the centripetal force needed to keep it moving at the same speed would need to be increased (2)- Lose 2
2a) They suspended the card from a pole (the pole went through the hole) and the card came to rest with it's centre of mass directly below its point of suspension. It did this as its weight had had a turning effect that returned it to its equilibrium position. Then they drew a line vertically down using a plumbline. Then, the repeated the proccess from a different point on the card and drew another vertical line down when the object came to rest and the place where the lines meet is the centre of mass (3)-Lose 1
4a) This happens because of the motor effect. The wire moves upwards when the switch is closed because current flows through the circuit and a magentic field forms around the wire and this interacts with the magnetic field from the magnet and repulses it so it moves upwards (2)-Lose 1
4c) The wires direction of movement would be reversed five times every second (2)-Lose 2
5b) The first notes is a smooth sound whereas the second notes is a sharp, brassy sound (1)-Lose 1
5d) Because they can only hear sound including and above 48 decibels so they need people to talk louder than in a normal conversation because the normal conversation is 45 decibels (2)-Lose 2
5e) Crosses across twenty from 250-20000 Hz (1)Lose 1
5f) Because it can damage their hearing (1)-Lose 1
8b) The star expand, becomes hotter and then cools to form a red giant. It then contracts and cools even more to form a white dwarf. (3)-Lose 2

it was a geostationary satellite because the orbit was 24 hours and it travelled horizontally. also, i did the audiogram different, the x's represented the lowest a person could hear so i put them all along the x axis, also i got the same as you for the moments question and i agree, stupid AQA