physics doubt CIE

[halosh92]

june 2005 paper 1:
 Q3
Q4
Q13

[astarmathsandphysics]

3. v=d/t=100/10=10
KE=1/2mv^2=1/2*80*10^2=4000 B
4)speed=40/2.5=16
I made this anser 16+-0.322
13)-2*5-2*10+3*20=30 A

[halosh92]

3. v=d/t=100/10=10
KE=1/2mv^2=1/2*80*10^2=4000 B
4)speed=40/2.5=16
I made this anser 16+-0.322
13)-2*5-2*10+3*20=30 A

thx! but am still unclear like for the 3rd one , how did u know that the time is 10 seconds?
and the second one i know how to get 16, but i couldnt reach for the uncertainty
and the 3rd one could u elaborate..like why did u choose these measurements to multiply with the forces?

[astarmathsandphysics]

I0 seconds cos this is what olympic athletes take to run 100m. For the last one it force x distance from P to the force

[halosh92]

Q16
Q22
Q25
Q32
Q33

[astarmathsandphysics]

Will answer this when I get home

[astarmathsandphysics]

Which paper are those questions from?

[tmisterr]

Q 16 Power is Energy/time, which is the gradient of the graph. Gradient is highest between 2 and 3 seconds. gradient is change in y/change in x so 30/1 which is 30W so answer is C
Q 25 intensity is directly proportional to (Amplitude)² so if you increase the intensity by 2, you also increase the Amplitude but by  square root 2 because of the above mentioned proportionality. answer is B
Q 32 Electric field strength=Voltage/distance between plates so 9/4*10^-3 which is 2250, to the nearest hundred it is 2300 or 2.3*10³. REMEMBER TO ALWAYS CHANGE mm into m.
Q 33 V=Area*length so lets say volume is Al. when you double the length (2l), you have to half the area (1/2A) so that 1/2A*2l=Al which is V (stays constant).  R=resistivity*length/Area so second wire will have 4 times the resistance so answer is D.

[tmisterr]

lol sorry solved 30 instead of 32
Q32 each electron carries a charge of 1.6*10^-19 so for a charge of 10C you need 6.25*10¹⁹ electrons to the nearest it will be 6.3*10¹⁹ answer is c