AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread]

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Reply 3960

Kkdhaliwal

First question I put the unit was equal to acceleration ?

Reply 3961

Qwerty1996

This was my order for multiple choice but some are definitely wrong

DAADDBCBABACDCACCBBABACBD

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Reply 3962

Fred Cantoni

Original post by Cmog

Was it steeper gradient with less area under graph, I forgot to adjust my current :angry:

Shallower gradient? the area should be the same as there was the same charge in the capacitor?

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Reply 3963

Mattniemier

What the **** was that

Reply 3964

Mudkipzz

Original post by michaelotty

This http://youtu.be/HV4FNXt1F6Y shows that without ring has heavier damping

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Yep, so damping was less when mass was added

Reply 3965

annierox1863

rate of change of momentum is m(v-u)/t units are ms-1/s which makes ms-2 so acceleration surely

Reply 3966

Cmog

Original post by Qwerty1996

This was my order for multiple choice but some are definitely wrong

DAADDBCBABACDCACCBBABACBD

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I got the same as you except for 2 :biggrin:

Reply 3967

Its Andy

Original post by Kkdhaliwal

First question I put the unit was equal to acceleration ?

Rate of change of momentum =mv/t

Therefore unit is kg * ms^-1 * s^-1 = Kgms^-2
This is equaivalent to mg (Kg * ms^-2)

Reply 3968

Fred Cantoni

Original post by annierox1863

rate of change of momentum is m(v-u)/t units are ms-1/s which makes ms-2 so acceleration surely

What about the kg from the mass

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Reply 3969

Fvthoms

Original post by Its Andy

It was a typo. You physically couldn't draw the graph as the current was so small.

The current was halved; I'm guessing one of your equations using factors of 10 were off by 3 magnitudes.

Edit: I stand corrected. Funny, I didn't see a typo on my exam.

(edited 8 years ago)

Reply 3970

kevincarreira

Original post by Cmog

Was it steeper gradient with less area under graph, I forgot to adjust my current :angry:

My friend and I both think it was a typo on AQA's behalf must have been 300 ohm or 150 kohm

Reply 3971

Qwerty1996

Original post by Cmog

I got the same as you except for 2 :biggrin:

No way!! That's so good! Are u confident in your answers?

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Reply 3972

Doomlar

The question about sketching the graph changed the resistance from 150 ohms to 300 kiloohms, which surely means that the initial current is 2000 times less, and the time constant is 2000 times greater, which must mean that the line would be almost straight and barely above the x-axis?

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Reply 3973

Cmog

Original post by Qwerty1996

No way!! That's so good! Are u confident in your answers?

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I was fairly confident with them before but this is great!

Reply 3974

Willow1.21

Original post by cudders96

Anyone else notice on the current graph question that the first resistance was 150Ω, but the second was 300KΩ? Think it was probably a typo on AQA's behalf, because the resulting graph would have to start with initial current 2000x lower than the original graph.