Physics Ppr1

[Jezla]

Could anyone plz explain the answers for these Questions:
Nov/2009/Ppr1/Q6,Q11,Q18,Q28 and Q37

http://www.xtremepapers.net/CIE/Cambrid ... 9_qp_1.pdf

 

[UxaiR]

question 11.
explaination: the total pressure inside the syringe is 300KPa beacause it is said that the pressure is 200kpa above atmospheric pressure which is 100kpa hance total pressure would be 300kpa.!!
when volume of syringe is doubled the pressure is halfed as pressure is inversly proportional to volume .!
so final volume would be 150kpa.!


Question 18
explaination: as you can see the surface is curved ,,, as evaporation would start the surface area would be reduced hence rate of evaporation would decrease.!

 

[UxaiR]

question 28.!
explaintion : as you can see that 4A of current is passing through 6 ohm resister and half of the 4A current would pass from other resister as resistance is doubled,which makes current to become half.!

so 2A of current would pass from 12 ohm resister.!
hence total current 4A + 2A = 6A current

 

[UxaiR]

question 28 .!
alternative way :
first calculate the potential difference of the circuit i.e V=IR
V=4 x 6
V=24

then calculate current in 12 ohm resister i.e V=IR
24= I (12)
I= 24/12
I=2A

hence total current = 2A + 4A
= 6A

 

[UxaiR]

Question 37


Explanation:
the battery is of 6 V,,the question say's that 2V is across the thermistor ,,this mean's that 4V would be there in the other resistor .!
from this we can calculate current in the series circuit i.e
V=IR
4= I (3000)
I = 4/3000
I =0.00133 A

in series circuit current is same throughout circuit

now calculate resistance in the thermistor i.e

V=IR
2 = 0.00133 (R)
R = 2/ 0.00133
R =1500 ohm



now from the graph see the temperature at 1500 ohm which would be 60`C

 

[sunshine]

UxaiR Nice work.!
it really helped me atleast.~

what about you Jezla???????

 

[Jezla]

YEp helped me a lot too.
Thanks loadz Uxair..