Physics P5 in 5 minutes !!!

[FRENZYAMU]

thanx bro it helps a lot........if u dont mind cn u help me with [papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_s11_qp_51.pdf] question 2 part b uncertainities ]

im a lady thanks a lot ,,,,

Q 2 part b,,,,first calculate 1/h then find uncertainity in h by the formula (DELTA)h/ h nd multiply this uncertainity with 1/h that u got b4....
eg for 400 +/- 5.....1/h will be inverse of 400 x 10 ^ -3 which is 2.5....now for the uncertainity calculate fractional error...5/400 (notice that 10^-3 in the denominator and numerator cancels out so u dont need to put it in calculation) =0.0125....now multiply this with ure final ans of h inverse i.e : 2.5 x 0.0125 =0.03125,,,,,there u go...uncertainity will be upto 1 s.f and the value will be to the same no# of d.p...therefore answer is 2.50 +/- 0.03


i really hope i havent made it very complicated

 

[kalpaveen]

im a lady thanks a lot ,,,,

Q 2 part b,,,,first calculate 1/h then find uncertainity in h by the formula (DELTA)h/ h nd multiply this uncertainity with 1/h that u got b4....
eg for 400 +/- 5.....1/h will be inverse of 400 x 10 ^ -3 which is 2.5....now for the uncertainity calculate fractional error...5/400 (notice that 10^-3 in the denominator and numerator cancels out so u dont need to put it in calculation) =0.0125....now multiply this with ure final ans of h inverse i.e : 2.5 x 0.0125 =0.03125,,,,,there u go...uncertainity will be upto 1 s.f and the value will be to the same no# of d.p...therefore answer is 2.50 +/- 0.03


i really hope i havent made it very complicated

im sry i didnt see that ur a girl....sry.......one more thing so when do we use the formula [{value+uncertainity} - {value-uncertainity}]/2 AND when should we use the fractional formula??? kind of confused with that....

 

[raamish]

hey guys just wanted to clear my doubts about plotting. in qs 2 of s07 when we calculate values of l2, i am having doubts in placing the points. for e.g the value of l2 (484) im plotting between the 480 and 490 points that is in half a square. So will my points be accepted or should i plot it in the 480 or 490 spot. It was given in the mark scheme that a 1/2 square plot was accepted. But i just want to clear my doubt. Can somebody help me?

 

[raamish]

Guys this is an answer to qs 1 of j07. I want to know the correct way of writing the answer. I have posted my answer to question 1 below. If there are any problems with my answer please tell me so that i can correct my answer. Thanku in advance.

In this experiment the independent variable is r and the dependant variable is v, the terminal velocity of the object. A constant variable in this experiment is temperature. Another constant variable is the distance when time is being measured.

We will calculate the diameter of the ball by using vernier calipers and then we will calculate the radius by using the formula d=r/2. We take metal balls of different radii to vary r. We measure the time taken for the ball to fall a fixed distance through the oil. To ensure the ball falls through a fixed distance we place fudicial markers on the container. We will measure the time taken for the ball to fall through two fixed points of the container at terminal velocity. Then we will calculate the terminal velocity of the ball by using the formula v=s/t. We will take multiple trials for each ball and then take out the average speed to reduce random errors in the experiment.
To ensure the ball has reached terminal velocity we will place fiducial marks well below the surface of the oil. We will take the diameter of the ball at different points of the ball and calculate the average. The oil used in the experiment should be clear and the container should be wide and transparent.
After calculating all the required values will plot a graph of v against r2. If the graph has a straight line passing through the origin then relationship has been confirmed. One safety precaution is to prevent the oil ffrom being near any fire because it may be flammable.

 

[Prince77]

PHYSICS P5 Q1! TIPS PLSS HELLP!!!

 

[FRENZYAMU]

im sry i didnt see that ur a girl....sry.......one more thing so when do we use the formula [{value+uncertainity} - {value-uncertainity}]/2 AND when should we use the fractional formula??? kind of confused with that....

i's alright
use the first one for logs and the second one when value is to be calculated either from division or multiplication, eg when R (resistance) is to be calulated from voltage V and current I, then R will be found out by V/I and uncertainity by adding their fractional errors and then multiplying by the R u got previously with their values...

let me brief u on errors :

1-ADDITION OR SUBTRACTION :
when 2 measurements are added or subtracted their errors are ALWAYS added up eg :
when u wanna add 2 +/- 0.2 and 3 +/- 0.2 then ure final answer shud be 6 +/- 0.4.....if u r asked to find the percentage error frm this then find fractional error and multiply with 100 like 0.4/6 = 0.06667 now multiply with 100 = 6.67%


2-PRODUCT :
(product of values) +/- (sum of fractional errors)(product of values)

eg for multiplying 5 +/- 2 with 10 +/- 2......after applying above formula ure answer shud come out to be 50 +/- 30


3-DIVISION :

(division of values) +/- (addition of fractional errors)(divsion of values)
eg for dividing 5 +/- 2 with 10 +/- 2......after applying above formula ure answer shud come out to be 0.5 +/- 0.5

4-CONSTANT POWER
(powered value) +/- (power x fractional error)(powered value)

eg if U = 4 +/- 0.2....find out U^2 then :
(4^2) +/- (2 x 0.2/4)(4^2)------> 16 +/- 1.6

 

[Silent Hunter]

anybody knows how to fill the secnd column of this paper : http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_53.pdf

the v^2 one ...... talking abut the uncertainties

thank you

FRENZYAMU
raamish

or anyone?

 

[FRENZYAMU]

hey guys just wanted to clear my doubts about plotting. in qs 2 of s07 when we calculate values of l2, i am having doubts in placing the points. for e.g the value of l2 (484) im plotting between the 480 and 490 points that is in half a square. So will my points be accepted or should i plot it in the 480 or 490 spot. It was given in the mark scheme that a 1/2 square plot was accepted. But i just want to clear my doubt. Can somebody help me?

the error bars are horizontal for this q right ?
i plotted the mid of 480 and 490.

 

[FRENZYAMU]

anybody knows how to fill the secnd column of this paper : http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_53.pdf

the v^2 one ...... talking abut the uncertainties

thank you

FRENZYAMU
raamish

or anyone?

u have the length of the card and u have t,,first calculate v and its uncertainity by (division of values) +/- (addition of fractional errors)(divsion of values)
and then use power formula for v^2 (powered value) +/- (power x fractional error)(powered value)

for the first one uncertainity = (0.05/0.046) +/- {(0.1 /5) + (0.002 /0.046)}x(0.05/0.046)(dis ws in cm) ----> 1.09 +/- 0.07....now use power formula,,, (1.09^2) +/- {2(0.07/1.09)}(1.09^2) nd bingo uncertainity ----->
1.2 +/- 0.2

 

[raamish]

Guys this is an answer to qs 1 of j07. I want to know the correct way of writing the answer. I have posted my answer to question 1 below. If there are any problems with my answer please tell me so that i can correct my answer. Thanku in advance.

In this experiment the independent variable is r and the dependant variable is v, the terminal velocity of the object. A constant variable in this experiment is temperature. Another constant variable is the distance when time is being measured.

We will calculate the diameter of the ball by using vernier calipers and then we will calculate the radius by using the formula d=r/2. We take metal balls of different radii to vary r. We measure the time taken for the ball to fall a fixed distance through the oil. To ensure the ball falls through a fixed distance we place fudicial markers on the container. We will measure the time taken for the ball to fall through two fixed points of the container at terminal velocity. Then we will calculate the terminal velocity of the ball by using the formula v=s/t. We will take multiple trials for each ball and then take out the average speed to reduce random errors in the experiment.
To ensure the ball has reached terminal velocity we will place fiducial marks well below the surface of the oil. We will take the diameter of the ball at different points of the ball and calculate the average. The oil used in the experiment should be clear and the container should be wide and transparent.
After calculating all the required values will plot a graph of v against r2. If the graph has a straight line passing through the origin then relationship has been confirmed. One safety precaution is to prevent the oil ffrom being near any fire because it may be flammable.

ok same as me. Hey can u check if my answer to qs 1 is correct that i posted on the top thanku.

 

[Prince77]

Physics P5 tips !

 

[kalpaveen]

i's alright
use the first one for logs and the second one when value is to be calculated either from division or multiplication, eg when R (resistance) is to be calulated from voltage V and current I, then R will be found out by V/I and uncertainity by adding their fractional errors and then multiplying by the R u got previously with their values...

let me brief u on errors :

1-ADDITION OR SUBTRACTION :
when 2 measurements are added or subtracted their errors are ALWAYS added up eg :
when u wanna add 2 +/- 0.2 and 3 +/- 0.2 then ure final answer shud be 6 +/- 0.4.....if u r asked to find the percentage error frm this then find fractional error and multiply with 100 like 0.4/6 = 0.06667 now multiply with 100 = 6.67%


2-PRODUCT :
(product of values) +/- (sum of fractional errors)(product of values)

eg for multiplying 5 +/- 2 with 10 +/- 2......after applying above formula ure answer shud come out to be 50 +/- 30


3-DIVISION :

(division of values) +/- (addition of fractional errors)(divsion of values)
eg for dividing 5 +/- 2 with 10 +/- 2......after applying above formula ure answer shud come out to be 0.5 +/- 0.5

4-CONSTANT POWER
(powered value) +/- (power x fractional error)(powered value)

eg if U = 4 +/- 0.2....find out U^2 then :
(4^2) +/- (2 x 0.2/4)(4^2)------> 16 +/- 1.6

thanx alot....now i totally get it......

 

[FRENZYAMU]

ok same as me. Hey can u check if my answer to qs 1 is correct that i posted on the top thanku.

yup totally right, i used an electromagnet switch which only gives a vertical velocity nd not horizontal nd u can add light gate arrangement as an enhancement of exp.

 

[raamish]

yup totally right, i used an electromagnet switch which only gives a vertical velocity nd not horizontal nd u can add light gate arrangement as an enhancement of exp.

yeah i have problem understanding what are light gates and when to use them in experiments. And can u also explain about the electromagnet switch u were talking abt?

 

[kalpaveen]

u have the length of the card and u have t,,first calculate v and its uncertainity by (division of values) +/- (addition of fractional errors)(divsion of values)
and then use power formula for v^2 (powered value) +/- (power x fractional error)(powered value)

for the first one uncertainity = (0.05/0.046) +/- {(0.1 /5) + (0.002 /0.046)}x(0.05/0.046)(dis ws in cm) ----> 1.09 +/- 0.07....now use power formula,,, (1.09^2) +/- {2(0.07/1.09)}(1.09^2) nd bingo uncertainity ----->
1.2 +/- 0.2

...

hey got another question........what if a value is given as 120+/- 5%......should we convert 5% into 0.05 and then find absolute uncertainty??.....this is a question from may/june 11 paper 52 q2 part e....

 

[fb.junks]

...

hey got another question........what if a value is given as 120+/- 5%......should we convert 5% into 0.05 and then find absolute uncertainty??.....this is a question from may/june 11 paper 52 q2 part e....

U will use .05 to calculate uncertainty..05 is equal to ratio of error in R/R

 

[FRENZYAMU]

yeah i have problem understanding what are light gates and when to use them in experiments. And can u also explain about the electromagnet switch u were talking abt?

light gates measure timings for a object to fall a particular distance..u have a light source on one end and a timer on the opposite, when a ball falls between them the light gets obstructed and the sensor on the other side no longer detects any light ( at this time ball is right infront of the timer), the timer starts,,,,having another such thing below this set up at a fixed distance h starts this second timer and the difference in readings from the first and second will be the time measured but u dont need to explain all of this in the procedure just say measure timings through light gates

for an electromagnet u OPEN the switch nd electromagnet no longer retains its magnetism letting go of ball..
im attaching a file, but remember in this case the ball is to be dropped from surface of oil to avoid a splash (a safety)
a simple setup is in oct 2009 paper 52

 

[FRENZYAMU]

...

hey got another question........what if a value is given as 120+/- 5%......should we convert 5% into 0.05 and then find absolute uncertainty??.....this is a question from may/june 11 paper 52 q2 part e....

U will use .05 to calculate uncertainty..05 is equal to ratio of error in R/R

yeah, what he said, in this case u dont need to find fractional error because percentages are already fractional errors converted into percentages

 

[Silent Hunter]

How to vary area A the indepedentant variable in the Q1 of this paper and i dont get what do they mean exactly by the area A ? is it the cross section area of the card board tube?

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w11_qp_53.pdf

FRENZYAMU
raamish

or any one ? thank you

 

[fb.junks]

How to vary area A the indepedentant variable in the Q1 of this paper and i dont get what do they mean exactly by the area A ? is it the cross section area of the card board tube?

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_53.pdf

FRENZYAMU
raamish

or any one ? thank you

Cross sectional area of the coil is to measured. And you can vary it by changing the radius of the coil and keeping the number of turns same.