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

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I didn't particularly enjoy that. It was okay, but not the best. I'm still hoping for 120 UMS but it's hard to tell how that went :dontknow:

Reply 3901

Fred Cantoni

What did people put of the damping question? I completely forgot what it was so I tried to work it out there, I put it has no affect?

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Reply 3902

Fred Cantoni

Original post by EmiratesCaptain

Thought it was good, what was the graph for current supposed to look like? I had the initial current below the first graph but just the same shape which im pretty sure is wrong

Pretty sure it had a lower initial current and then a less steep gradient as time constant was greater?!

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Reply 3903

Fvthoms

Original post by Fred Cantoni

Pretty sure it had a lower initial current and then a less steep gradient as time constant was greater?!

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I thought the same; but was told by my peers that the current had the same start point.

Reply 3904

chasvortex

Little questions:
Gravitational potential is a vector isn't it?
I put the oscillations were less damped with the metal ring - thoughts on this? I reasoned the air resistance force would be constant but as F=ma, the pendulum would deccelerate more slowly so would be less damped.

Reply 3905

EmiratesCaptain

Original post by Fred Cantoni

What did people put of the damping question? I completely forgot what it was so I tried to work it out there, I put it has no affect?
It has no effect from the equation of time period of a simple pendulum (at least i think?)

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It has no effect from the equation of time period of a simple pendulum (at least i think?)

Reply 3906

Fred Cantoni

Original post by Fvthoms

I thought the same; but was told by my peers that the current had the same start point.

Why would it? If you simplify it and treat it like a battery for the same voltage but huger resistance it would have a lower current, why wouldn't that hold for a capacitor?

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Reply 3907

simonli2575

Original post by Fred Cantoni

What did people put of the damping question? I completely forgot what it was so I tried to work it out there, I put it has no affect?

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There's more damping without the ring because the ring increases the pendulum's weight and the resistance's effect will be decreased.

Reply 3908

StarvingAutist

Original post by Fred Cantoni

What did people put of the damping question? I completely forgot what it was so I tried to work it out there, I put it has no affect?

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Less damped with ring because of conservation of momentum.

Reply 3909

Fvthoms

Original post by Fred Cantoni

Why would it? If you simplify it and treat it like a battery for the same voltage but huger resistance it would have a lower current, why wouldn't that hold for a capacitor?

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I agree, but to be honest; my memory of the paper is already hazy; and as I have said on the student room before:

"If enough people tell you that 1+1=2, you should start to doubt if it's really 3"

Edit: they seem to think that it was the capacitance that was increased.