How did Physics M/J '17 52 go?

[Irfanhaider0533]

Yes

And measure mass with balance.

 

[Talha Sial]

I took F as Independent and R as Dependent and found the values of R after varying F above the maximum F.

 

[Zaina Tariq]

I got y-intercept around 7. Uncertainty around 3.

And yes, also smooth surface anyone? For q1.

straight line. always when doing Q1

 

[Syed Umar]

straight line. always when doing Q1

?

 

[Irfanhaider0533]

?

She means that you have to convert the relationship into an expression which can be used to plot a straight line graph. In this case it was f against 1/r

 

[Syed Umar]

She means that you have to convert the relationship into an expression which can be used to plot a straight line graph. In this case it was f against 1/r

Oh, I know that. I had asked if anyone used smooth surface for turntable, so couldn't get how the straight line worked in.

 

[Zaina Tariq]

She means that you have to convert the relationship into an expression which can be used to plot a straight line graph. In this case it was f against 1/r

yup.

 

[techgeek]

I wrote r as independent variable and f as dependent
plotting a graph r against 1/f
straight line passing through origin
Keep mass of cube constant
I drew the turntable and a top pan balance .
since the turntable was connected to electric motor I thought it'd be too fast to count manually
so I connected to OCR to measure frequency, not sure though?!
I also wrote to use same turntable so the surface is same
K was gradient x m4pi^2
and to use ruler to measure r
but for question 2, my unertainty was even greater than the y-intercept itself
and uncertainty for Q was as large as 122% (omg! I know it can't be! but I couldn't find any mistake)

 

[Syed Umar]

I wrote r as independent variable and f as dependent
plotting a graph r against 1/f
straight line passing through origin
Keep mass of cube constant
I drew the turntable and a top pan balance .
since the turntable was connected to electric motor I thought it'd be too fast to count manually
so I connected to OCR to measure frequency, not sure though?!
I also wrote to use same turntable so the surface is same
K was gradient x m4pi^2
and to use ruler to measure r
but for question 2, my unertainty was even greater than the y-intercept itself
and uncertainty for Q was as large as 122% (omg! I know it can't be! but I couldn't find any mistake)

Yep, I used a CRO, too.

 

[Tozu Fofo]

I wrote my independant and dependant variable will my whole Q1 be wrong? =(

 

[Mursalin15]

I wrote F as independent and r has dependent.
Mass constant, measure using top pan balance.
vary frequency by differing voltage across a resistor.
Place mass at point r and increase frequency until r moves.
note the voltage and count 20 oscillations to calculate the time period and find frequency by 1/T
repeat the experiment with increasing values of f and its corresponding values of r.
plot a grpah r againts 1/f
use safety screen and use fiducial markers on the table to observe the change in position of cube.

*my confusion is in the part that technically i am changing r and i gave a downward sloping curve cause as we know centripetal force increases with increasing r, so frequency increase , r must decrease.
is this idea wrong?

 

[Tozu Fofo]

I think I wrote the wrong dependant and independant variable. I wrote keep mass of cube constant and density. Current and potential difference across motor should be constant. Measure r with ruler and m with balance. Clean surface of turntable. Use safety screen to protect hair being trapped in turntable. And then of motor to avoid overheating. I said use alternate power supply with variable frequency signal generator. Reading frequency of generator. Measuring r when cube stabilizes. I wrote plot a graph between 1/r and f. Relationship valid if straight line from origin. Keep current constant using rheostat and ammeter. Cathode Ray Oscilloscope can be used to measure frequency to by multiplying number of blocks with timebase settings and then doing 1/t to get f. I wrote that pass a small enough frequency to produce measurable value of r and repeat experiment for values of Frequency and take average r. I already feel quite upset, but have I salvaged some marks or E.C.f ? Because I thought it said cube does not move relative to motion of turntable

 

[Ecosora]

Hi. I wrote that f is independent and r is dependent but i varied r and recorded f will i get mark?

 

[hamza3256]

Oh! Am i the only that got Y-intercept as 1.00 with uncertainty of 0.1 (can't remember the uncertainty properly). and for the E value I got 6.9 and Q was around 7.

 

[techgeek]

Oh! Am i the only that got Y-intercept as 1.00 with uncertainty of 0.1 (can't remember the uncertainty properly). and for the E value I got 6.9 and Q was around 7.

my y-intercept was big, around 7 and uncertainty was even bigger :/

 

[Ecosora]

I got y-intercept 4.45 and uncertainty 0.2 and for E and Q 1.4 and 1.6

 

[rahimshah98]

Can we even use CRO with dc motor.?
I used a video camera with slow motion playback to measure time period.
My y-intercept had like a 0.78 uncertainty and percentage uncertainties were also quite ordinary around 20-40%

 

[Tozu Fofo]

Q WAS Y INTERCEPT MULTIPLIEF BY E (RECIPRICOL OF GRADIENT) WAS ABOUT 40 OHMS AND PERCENTAGE ERROR OF 44 TO 50 PERCENT.

 

[rahimshah98]

Yeah, and E was 7.14 Volts for me with percentage uncertainty around 20-30%

Q WAS Y INTERCEPT MULTIPLIEF BY E (RECIPRICOL OF GRADIENT) WAS ABOUT 40 OHMS AND PERCENTAGE ERROR OF 44 TO 50 PERCENT.

 

[Tozu Fofo]

Same but percentage uncertainty not that high for me was of 7%