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physics paper 3, harder than hard

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what is the answer for the first question in radioactivity?
the one on how the reading doesn't decrease but increases?
they will mark on two specific points - BACKGROUND radiation and spontaneousness on radioactivity.
a similar question came in a previous year, so I knew this was the way to answer it:

the radiaoactive substance had decayed to a stable particle, but the counts reading did not decrease and there was still background radiation (youcan mention some sources of it too). the reading increased a bit too as radioactivity is random or spontaneous, so the background radiation can spike at times.

note : by an increase they dont mean a huge increase, just minor ups and downs as you could see in the graph. hence the best fit line was drawn.
 
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the one on how the reading doesn't decrease but increases?
they will mark on two specific points - BACKGROUND radiation and spontaneousness on radioactivity.
a similar question came in a previous year, so I knew this was the way to answer it:

the radiaoactive substance had decayed to a stable particle, but the counts reading did not decrease and there was still background radiation (youcan mention some sources of it too). the reading increased a bit too as radioactivity is random or spontaneous, so the background radiation can spike at times.

note : by an increase they dont mean a huge increase, just minor ups and downs as you could see in the graph. hence the best fit line was drawn.
how many marks u expecting???
70??
 
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yeah, same here . :) and which way would the statue move, anti-clockwise or clockwise ? I said clockwise, I wrote about stability.
 
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yeah, same here . :) and which way would the statue move, anti-clockwise or clockwise ? I said clockwise, I wrote about stability.
i wrote anticlockwise and returning to equilibrium.....it was just a guess though :p
 
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And to get the half-life, you never have to subtract the back-ground radiation. You're suppose to multiply 52 x 1/2= t1 and again 52x1/4= t2. The mean average of t1+t2/2 = Half-life. :)
 
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I got 33. % , not 25%. :)
becuz u wrote in the denominator ...only the power LOSS .. u didnt add the USEFUL POWEROUTPUT to get the TOTAL POWER INPUT .... u just put the value from the mgh in this n left it like that !! but in the question its clearly stated ! TAKE THIS AS THE POWER LOSS / second !!!
so u will have to add the useful power to get the total power output :p :) :D :eek:
 
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And to get the half-life, you never have to subtract the back-ground radiation. You're suppose to multiply 52 x 1/2= t1 and again 52x1/4= t2. The mean average of t1+t2/2 = Half-life. :)
i messed up that question and got 2.6 days which would be woefully wrong :(
still if i get 60+ i think and A* is likely since i don't think i lost more than 3 marks in p1 and hope to do well in p6 :D
 
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becuz u wrote in the denominator ...only the power LOSS .. u didnt add the USEFUL POWEROUTPUT to get the TOTAL POWER INPUT .... u just put the value from the mgh in this n left it like that !! but in the question its clearly stated ! TAKE THIS AS THE POWER LOSS / second !!!
so u will have to add the useful power to get the total power output :p :) :D :eek:
You got it the other way around, you they gave you a %. Your total energy input was your mgh=E. You suppose to multiply that with the percentage to get the useful power output. You divide that by total energy input, and I guess it comes- 33.1 or 33.3 %. I forgot. What did majority get ?
 
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You got it the other way around, you they gave you a %. Your total energy input was your mgh=E. You suppose to multiply that with the percentage to get the useful power output. You divide that by total energy input, and I guess it comes- 33.1 or 33.3 %. I forgot. What did majority get ?
i did 10400/something and multiplied it by a 100....:p
what abt the t-shirt question....it was all based on evaporation
 
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You got it the other way around, you they gave you a %. Your total energy input was your mgh=E. You suppose to multiply that with the percentage to get the useful power output. You divide that by total energy input, and I guess it comes- 33.1 or 33.3 %. I forgot. What did majority get ?
the total energy input was .. the loss + the useful power
they said mgh= loss /sec .. then u add the useful power !
then u get the total power output
 
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Yeah. The T-shirt question was easy I guess. More wind, more evaporation. The other one was folded, so less surface area.
 
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the total energy input was .. the loss + the useful power
they said mgh= loss /sec .. then u add the useful power !
then u get the total power output
Not sure man. Lets see what majority of the people got ? :)
 
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