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Official OCR A2 G484 June 2016 [Module 1] [90UMS]

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What did people get:
-for why areas were different?
-what 2 things forces in N3 law are common
-what 2 things forces in N3 are different
-what happened to speed if moon was closer to planet
-energy changes
-2 assumptions for the experiment
-how does internal energy relate to temp
Reply 221
Avatar for Oddowl
Oddowl
Original post by tochicool
The mass is doubled so the energy supplied per inversion is doubled but you require twice the energy to heat up twice the amount of matter for the same temparature rise.

If that makes sense.


Thanks, it does make sense now
I got 2.5x10^28
Peoples opinions on grade boundaries inc 90/90 UMS..
Reply 224
Avatar for Jm098
Jm098
2
Original post by socketlicker
I got 2.5x10^28

I got that as well! What did you do?
Original post by Willward1998
Did anyone get 1.73 x 10^33 for the mass of S2?


I did :smile:
Original post by Jm098
Anyone get like 0.597 for the period?


I did! Calculated in degrees and then converted
Fair to hard paper imo, more difficult than previous years. The binary star first page threw me as did the fireman's hose. For the latter everyone seems to be getting 1070 but that is from adding (8.25 x 25 x sin 55) and 92g, I thought it was 92g - (8.25 x 25 x sin 55)?
Original post by banksy0312
...23? :/


i think i got to the power of 23 too
Original post by Reda2
I thought it was not bad, but there were literally almost no normal questions, like define this, why this. All questions seem to have a twist, lost most marks on that flipping alphabet question, but other questions was all good. I think I'm above the A threshold.

But man if I had gotten that question I would be flying right now.


Right there with you man, **** binary systems. The mechanics stuff threw me a bit too, think I dropped 14 marks in missed questions, but might have managed to scrape a few back by doing some working. Everything else went swell, had about 25 minutes spare time for those missed questions.
(edited 7 years ago)
Original post by Siddhart1998
What did people get:
-for why areas were different?
-what 2 things forces in N3 law are common
-what 2 things forces in N3 are different
-what happened to speed if moon was closer to planet
-energy changes
-2 assumptions for the experiment
-how does internal energy relate to temp


Areas were different because distances of bounces were different
In common - same type, same time, same magnitude
Different - different bodies, opposite direction
I think if the moon was closer it's period would get smaller
My assumption were KE = GPE perfectly, and that all beads fell from the same height
Internal energy is directly proportional to temp E = (3/2)kT
Original post by Mathematicus65
Peoples opinions on grade boundaries inc 90/90 UMS..


41-B 45-A 49-A* 53-Full?
Original post by Siddhart1998
What did people get:
-for why areas were different?
-what 2 things forces in N3 law are common
-what 2 things forces in N3 are different
-what happened to speed if moon was closer to planet
-energy changes
-2 assumptions for the experiment
-how does internal energy relate to temp


Areas were different as area represents total displacement, and the ball has lost energy after first bounce so will not bounce as high
Forces in common = same type of force (e.g gravitational) and of the same magnitude
Differences = act on different objects, and act in opposite directions

Those ones I'm pretty certain on, not sure about others
Original post by TheFarmerLad
Fair to hard paper imo, more difficult than previous years. The binary star first page threw me as did the fireman's hose. For the latter everyone seems to be getting 1070 but that is from adding (8.25 x 25 x sin 55) and 92g, I thought it was 92g - (8.25 x 25 x sin 55)?


I agree; resolving vertically generates the equation
R + force upward on fireman from hose pipe = Weight
Hence R = Weight - force upward from hose pipe
How did you folks draw the KE/EPE graph? Differences of opinion at school
Original post by TheFarmerLad
Fair to hard paper imo, more difficult than previous years. The binary star first page threw me as did the fireman's hose. For the latter everyone seems to be getting 1070 but that is from adding (8.25 x 25 x sin 55) and 92g, I thought it was 92g - (8.25 x 25 x sin 55)?

The floor's reaction force upwards has to counteract the weight of the man down and the force of the hose pushing him down to keep him in equilibrium, so the reaction force has to be equal to both the weight and the vertical component of the hose pushing the man down. That's what I made of it anyways
Original post by Siddhart1998
What did people get:
-for why areas were different?
-what 2 things forces in N3 law are common
-what 2 things forces in N3 are different
-what happened to speed if moon was closer to planet
-energy changes
-2 assumptions for the experiment
-how does internal energy relate to temp


-Areas different as area v*t represents distance travelled, hence different distances were travelled during these line segments of time.

- Common: forces are equal in magnitude and must be of same type (e.g. both gravitational).

-Different: Forces are opposite in direction and must be acting on different bodies.

-If moon spirals closer to planet, orbital radius would decrease so time period would also decrease as t squared proportional to r cubed (kepler's law). Hence as v is inversely proportational to t, as t decreases, the speed of the moon increases.

-Gravtiational potential energy of the lead pellets is converted to their kinetic energy.

-Assumptions are that all the gravitational potential energy was converted to kinetic energy and not other energy forms AND also that there was no heat (thermal energy) loss to the tube and the air inside/outside of it - i.e. no energy used heating up the air/tube.

-Internal energy is the sum of the randomly distributed kinetic and potential energies of the molecules of a system, and internal energy is directly proportional to the absolute temperature in kelvin of the ideal gas.

(Hope these are right!!)
Original post by The-Spartan
The mass of S2 was 1.03 * 10^33


I do hope that is correct, it was the last thing I wrote on my paper. I skipped that question and came back to it.
Original post by Artmanlikesart
Areas were different because distances of bounces were different
In common - same type, same time, same magnitude
Different - different bodies, opposite direction
I think if the moon was closer it's period would get smaller
My assumption were KE = GPE perfectly, and that all beads fell from the same height
Internal energy is directly proportional to temp E = (3/2)kT


For assumptions, what about no energy being used to heat the glass tube and the air inside of it? Not sure if that would get a mark :/
Original post by Siddhart1998
What did people get:
-for why areas were different?
-what 2 things forces in N3 law are common
-what 2 things forces in N3 are different
-what happened to speed if moon was closer to planet
-energy changes
-2 assumptions for the experiment
-how does internal energy relate to temp


- Areas represent vertical height of ball. After bouncing height is less than when ball is originally dropped so area of triangle is smaller.

- Worded weirdly this qu. Common : equal and opposite I gave two examples which were gravity and normal reaction
Different : Has to be same type of force e.g can't be normal and weight. Can't be if object is accelerating
- Force increases therefore v increases as v^2 pro to f
- GPE lost = KE Gained KE pro to temp so gain in KE = prop gain in temp
- All thermal energy supplied to balls, assumed no change in temp to tube. Assume all balls behave the same/each ball undergoes the exact energy changes as calculated (not sure about this)
- Same idea that KE prop to temp, and in an ideal gas, no potential energy so all energy of molecules = KE

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