Physics IGCSE Edexcel May 25th 2016.

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Reply 80

tomtimpson

Original post by yeknodelttil

I'm 90% sure it is kinetic though as I got this wrong in a past paper from a few years ago :/

Yeah, probably, bit misleading the way they write it tho

Reply 81

Speersy

Cant remember the test well enough to make a proper mark scheme but this may be useful for those wanting to create one
1a) horizontal bit of line shows constant speed
b) area under graph shows distance
c) distance over time
2a) light/thermal (maybe KE) is released
b)Purpose of moderator (2) moderator slows down fast neutrons so they can be absorbed by the nuclei
c) Expain a controlled nuclear reaction (3) control rods absorb neutrons released from each fission, slowing down reaction and preventing the rate of reaction increasing exponentially out of control

Then can't remember actual question numbers from here on out:
Velocity of train based on KE and mass is 8 point something

Sound Questions:
45,000Hz is ultrasound
Why is equation halved(2) The sound has to bounce to the person's organs and then back so it travels twice the distance
What happens to wavelength when speed of sound increases?(2) Frequency stays constant so wavelength increses because of wave equation

Hooke's law question: (5)
- add known value of masses each time
-measure length of spring
-find extension(trust me this is a mark because Im copying this from the mark scheme of a past paper)
-draw graph
-detail of spring measurement e.g hold ruler vertical
-make sure stationary before reading
- repeat with same masses
-check value of masses on balance

Astronomy Questions:
Draw a loop to finish the orbit
draw an X really close to where you drew the orbit line
Comet cant be seen when its behind the Sun
The distance between each dot tells us the speed of the comet as the comet travels more in the same unit time between week 3 and 4

Measuring Circle Questions:
A few calculations
Then: explain the difference in readings of digital calliper and the string measurement (4)
-Digital calliper more accurate and did not make human error
- rope was wrapped around and therefore had a bigger circle and a bigger circle was measured(if that makes sense)
-Student may have read the ruler wrong
-Digital calliper was more precise and measures to the neares hundreth of a millimeter

Passengers climb up lift of station and gain GPE by doing work and climbing Earth's gravitational field (2)

The train's brakes do less work because the train slows down going up the hill and loses KE, The motor does less work because gravity accelerates the train coming down the hill (4)

Why does the refractive index have no units (2) It is relative to the speed of light in a vacuum which equals 1 while it is also the factor by which light slows down by
Why does the graph not start at zero?(2) refractive index cant go below 1 and the minimum value recorded for angle of incidence was above 20

How does polar bear conserve heat? (2) Polar bear traps air which is a good insulator and stops convection

Properties of white fur and black skin (3)Black skin = good absorber and emitter(both loss and gain of thermal energy for polar bear) white fur= poor emitter

Polar bear hair tubes of air: (3)
refractive index of air is too low
light will exit out of tube
as light is below critical angle

Pretty sure most of the other questions are calculations or rearranging formulae

(edited 7 years ago)

Reply 82

ApricotMarmalade

nuclear fission releases kinetic energy

Reply 83

P__K

Original post by Speersy

I'm pretty sure the white fur reflects heat radiating from the skin back as well

Reply 84

conradliebers

http://www.thestudentroom.co.uk/showthread.php?t=4118187

Reply 85

BigManDR

Original post by Speersy

What did you guys put for the reason why passengers gain GPE when going underground in a lift?

I said that they were gaining GPE by resisting the gravity of the ground above them by going underground
But then they'd still be losing GPE on the whole because they're going underground - annoying question!

i think they were going up the elevator tho?

Reply 86

Speersy

Original post by BigManDR

i think they were going up the elevator tho?

It definitely said in the question the lift takes people DOWN but i have a feeling that the answer is that they gain GPE on the way up

Reply 87

anguslurcott

THIS WAS HORRIBLE- Enough said!

Reply 88

Pink_Sparkles

Original post by Speersy

It definitely said in the question the lift takes people DOWN but i have a feeling that the answer is that they gain GPE on the way up

hello!!!!
i wanted to ask something
how can it be kinetic didn't the question pointed specifically towards the coolant ???

Reply 89

igggy

does anyone know how they mark it u but two points and the first is right and the second is wrong? Do you get the mark?

Reply 90

igggy

Original post by Speersy

It definitely said in the question the lift takes people DOWN but i have a feeling that the answer is that they gain GPE on the way up

nah it said from platform to street level

Reply 91

Speersy

Original post by shahida sulaiman

hello!!!!
i wanted to ask something
how can it be kinetic didn't the question pointed specifically towards the coolant ???

Thermal energy is the Kinetic energy of the molecules and technnically they are the same thing because thermal energy is just KE at a small scale so I think the mark scheme will accept KE

Reply 92

Ranveen Pandhal

Original post by Mark 88

THE WORST EXAM POSSIBLE
So hard! What are Edexcel doing?

Posted from TSR Mobile

Tell me about that!!! 😁😁😁

Posted from TSR Mobile

Reply 93

cornflakeexpert

Original post by Speersy

Who got the question on what happens to the wavelength of sound waves when they are sped up?
I think i said that the the fisrt part of the wave at the front gets sped up first so it accelerates away from the waves behind it so the wavelength increases

wavelength increases because wave speed = frequency x wavelength

Reply 94

Isa753

I had done a previous past paper and it said kinetic energy is given off??

Reply 95

aelliot

Taking Paper 1 into account, what topics can we expect in paper 2? Moments & momentum seem pretty standard for P2, what else?

Reply 96

P__K

Original post by aelliot

Taking Paper 1 into account, what topics can we expect in paper 2? Moments & momentum seem pretty standard for P2, what else?

Other than moments and momentum, possibly electrostatics and (electro)magnetism

Reply 97

Ranadosa

Original post by P__K

Other than moments and momentum, possibly electrostatics and (electro)magnetism

can someone help me with momentum? I don't think i get the concept, i try and memorise it but obviously doesn't work

Reply 98

Bede735

Original post by Ranadosa

can someone help me with momentum? I don't think i get the concept, i try and memorise it but obviously doesn't work

There are 2 things to remember. Whatever it is in any collision it is conserved - so take the direction the objects are travelling in into account.

Then it is just a before and after question p_before = p_after ; practice these questions

Secondly it's how Newton defined his 2nd Law - more to the point it IS the 2nd Law.

f = m a
= m(v - u)/t
= (mv - mu )/ t
= change in momentum / change in time
= rate of change of momentum

No matter the application, just say if you slow the collision down (increase t) you decrease the average force making it safer/less likely to cause injury and quote the formula above. Doing this will always gain a mark or two.