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OCR Physics A - G484: The Newtonian World - 18/06/12

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Reply 100

gherrick

i cant seem to be able to see the past papers on the OCR website!? :eek:

help please :confused:

i cant download from media fire either, this is not good :frown:

thanks for any help

Reply 101

lavinia_7

Original post by gherrick

i cant seem to be able to see the past papers on the OCR website!? :eek:

help please :confused:

i cant download from media fire either, this is not good :frown:

thanks for any help

which papers do you need?

Reply 102

rr52

Original post by Jukeboxing

Go to post #22

Thank you

Reply 103

crazy1234

Original post by welshy93

my text book says that the frequency of an oscillation doesn't change when damping is introduced as it's a characteristic of SHM but then it says the natural frequency is shifted to a lower value so resonance occurs sooner in a damped system can anyone explain please?

Two things, the frequency of oscillation just 1/T, when damping is introduced, the frequency does not change, but he amplitude decreases.
The natural frequency and resonance, is to do with an external driving force, causing an object to oscillate. So when the natural frequency=external driving frequency it resonates. The natural frequency differs depending on the object being oscillated. When damping is introduced, the natural frequency falls not the frequency at which it actually oscillates. Therefore it resonates at a different driving frequency.

I hope that makes sense :smile:

Reply 104

welshy93

Original post by gherrick

i cant seem to be able to see the past papers on the OCR website!? :eek:

help please :confused:

i cant download from media fire either, this is not good :frown:

thanks for any help

if the pdf files aren't opening update adobe reader for your browser, that's what i had to do :smile:

Reply 105

Brap4k22DivideBy2

Original post by crazy1234

Spot on. An experiment for this would be Barton Pendulums?

Reply 106

welshy93

Original post by crazy1234

yeah completely, thank you! :biggrin:

Reply 107

crazy1234

Original post by Brap4k22DivideBy2

Spot on. An experiment for this would be Barton Pendulums?

Yeah it is. I cant quite remember exactly how it works. But is it something to do with swing one pendulum, and out of the other pendulums, one will resonate and oscillate with a large amplitude so its got an natural frequency equal to that of the one being swung. Is that right...

Original post by welshy93

yeah completely, thank you! :biggrin:

No problem :smile:

Reply 108

Brap4k22DivideBy2

Original post by crazy1234

Yep.

Reply 109

jahani08

do we need to know an experiment that demonstrates damping?

Reply 110

Holby_fanatic

Originally Posted by cepti
Does increasing the pressure raise the internal energy of a gas?

PV = nRT (NkT)
As Pressure increases, the temperature increases.

From the equation E = 3/2 kT, equating it with the equation for kinetic energy.

As the temperature increases, so does in the kinetic energy.

Internal energy is the sum of the potential and kinetic energies.

Therefore as Kinetic energy increases, so does internal energy.

( I think this is right, Im not sure though)

Our teacher just told us to always do it in terms of the temperature remaining constant.

So if the pressure increases, for the temperature, and therefore kinetic energy, to remain constant, the volume must fall. Potential energy decreases and so the internal energy decreases.

This was posted from The Student Room's Android App on my GT-S5360

(edited 11 years ago)

Reply 111

Brap4k22DivideBy2

Can someone explain 3)B) II. On Jan 12 paper. Mark scheme doesn't help me....

G484 MS JAN 12.pdf143.4KB

G484 JAN 12.pdf173.5KB

Reply 112

welshy93

Original post by Brap4k22DivideBy2

Can someone explain 3)B) II. On Jan 12 paper. Mark scheme doesn't help me....

for the moon T= 2358720 put this into t^2 = (4 x pi^2/G x 6x10^24)r^3
rearrange for r which = 3.83x10^8
then 3.83x10^8 / 4.23x10^7 = 9.07
4.23x10^7 was found in previous part
hope that helped :smile:

Reply 113

Picture~Perfect

Original post by Brap4k22DivideBy2

Can someone explain 3)B) II. On Jan 12 paper. Mark scheme doesn't help me....

I wouldn't worry about it too much, it's a stretch and challenge question aimed at A* candidates and it will not come up again.

Reply 114

Picture~Perfect

Original post by jahani08

do we need to know an experiment that demonstrates damping?

No, you just have to be able to explain the effects of damping.

Reply 115

welshy93

Original post by Holby_fanatic

It is right, but our teacher just told us to always do it in terms of the temperature remaining constant.

So if the pressure increases, for the temperature, and therefore kinetic energy, to remain constant, the volume must fall. Potential energy decreases and so the internal energy decreases.

This was posted from The Student Room's Android App on my GT-S5360

I thought gases have no epe cause the bonds are completely broken so even if the volume decrease the epe remains 0 because it's still a gas?

Reply 116

Holby_fanatic

Original post by welshy93

I thought gases have no epe cause the bonds are completely broken so even if the volume decrease the epe remains 0 because it's still a gas?

That is only true for ideal gases.
I was going about it in terms of normal gases.

This was posted from The Student Room's Android App on my GT-S5360

Reply 117

Brap4k22DivideBy2

Original post by welshy93

for the moon T= 2358720 put this into t^2 = (4 x pi^2/G x 6x10^24)r^3
rearrange for r which = 3.83x10^8
then 3.83x10^8 / 4.23x10^7 = 9.07
4.23x10^7 was found in previous part
hope that helped :smile:

Where did you get 2358720 from?

Reply 118

sarah-xx

Can someone help me on the first question of the June 2010 paper?
In an inelastic collision, momentum is conserved, but kinetic energy is not.
So I ticked the box where it says 'after the collision, the objects have the same momentum'. But this is not correct. The correct answer was 'total energy is conserved'.
So why am I wrong, if the definition for an inelastic collision says that kinetic ENERGY is not conserved?
Please help! I might be reading the question in a weird way or something though...

Paper:
http://pdf.ocr.org.uk/download/pp_10_jun/ocr_57572_pp_10_jun_gce_g484.pdf?

Mark Scheme:
http://pdf.ocr.org.uk/download/ms_10/ocr_56262_ms_10_gce_g484.pdf?

Reply 119

Jukeboxing

Original post by sarah-xx

Principle of conservation of energy:
Energy cannot be created or destroyed, it can only be transformed into other types of energy.

While k.e may not be conserved, the total energy is conserved. Its just that some of that k.e has transformed into heat, chemical energy etc.

Objects wont necessarily have the same momentum after a collision, they both have the same impulse (i.e change in momentum).