Physics: Post your doubts here!

[Soldier313]

What is the speed of an alpha particle? is it 0.1(3x10)^8?? and what about the speed of beta particles?

 

[perkypearl]

anyone can help me to do oct/nov 2007 Q#2 and Q#1(b)
http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_w07_qp_2.pdf

 

[Soulgamer]

Please someone solve Q.4 d (i) and (ii)

http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_s07_qp_2.pdf

With explanation and diagram of-course. Thank you!

 

[hussamh10]

anyone can help me to do oct/nov 2007 Q#2 and Q#1(b)
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_2.pdf

Q1 )b First of all find out the radius which is 0.488
Then Work out the uncertainity
Delta R/R=DeltaV/V +DeltaL/L
Delta R/0.488=0.5/15+0.1/20
We will get Delta R=0.018706 ---->Now this is the uncertainity of R^2 so we will divide it By 2 to get the Uncertainity Of R
Delta R=0.018706/2------>0.00935
Radius =0.488 +/- 0.009

 

[Navi Don]

please explain me how to make two waves in a same graph paper which have same phase angle eg 30 degree phase angle.how to make?

 

[haroon740]

Is current Vector or Scalar ?

 

[Saad (سعد)]

Is current Vector or Scalar ?

Scalar.

 

[Soldier313]

Can someone please help me with qn 7 and please provide drawings if possible...
qn paper: http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s11_qp_21.pdf
ms: http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_s11_ms_21.pdf
thanx soo much....

 

[haroon740]

Hey people i have an important question.. Does number of significant figures matter in phy paper 2? If answer scheme gives 2sf for final answer but i gave in 3sf, do i lose any mark?

yeah ih does when they specifically ask for 3 S.F and u lose one mark ,but normally its best to give your answers to 3 s.f and also look at the figures in the question if they are upto 3 s.f then go for 3s.f.

Welcome

 

[blabla]

how many significant figures do we have to give when calculating uncertainty?

 

[Soldier313]

reposting my question....can someone please help?

Can someone please help me with qn 7 and please provide drawings if possible...
qn paper: http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_21.pdf
ms: http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_ms_21.pdf
thanx soo much....

and also i need to know the speed of alpha and beta particles
thanx a lot.....God bless

 

[Soldier313]

how many significant figures do we have to give when calculating uncertainty?

depends on the qn.....if u refer to mj/11 qp 21 , the sgf of the uncertainty in 1c.) is 1 sgf for the resistivity just lyk the resistance from the qn........so basically i am not sure but i think it's diff fr diff qns

 

[Peter Check]

Please someone solve Q.4 d (i) and (ii)

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s07_qp_2.pdf

With explanation and diagram of-course. Thank you!

First draw a rough right angled triangle(drawn in blue) and label the the hypotenuse base and height with their according speed, Now make a scale lets say 5m/s - 5boxes in the graph( I have used cms in my example). Now convert your velocities into box units,(which is basically 18m/s =18boxes) Now draw the right angled triangle again(drawn in red), this time on the graph and according to the box units. Then find the angle using a protractor( you can use trigonometry to make sure your angle measured is indeed correct)

 

[Peter Check]

Is there any regulation to how many significant figures you can leave your final answer to? For instance finding out uncertainties in question 1 for http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_22.pdf, the answer sheet denies a mark if I do not write the answer to the significant figure they want, while in part a. they accept 3 s.f, in part b,I get a mark only if if i write the answer to two s.f. so how the hell do i know what they want? (http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_ms_22.pdf)

 

[Mad-Eye]

please explain me how to make two waves in a same graph paper which have same phase angle eg 30 degree phase angle.how to make?

one complete cycle is 360 deg. so half a wave will be 180 deg. if you start second wave at half point of the first one, you create a phse difference of 180. a quarter you get 90 deg. a thisrd of the quarter and you get 30 deg phase difference. If you still don't get it ask me and I will explain with figures.

 

[Mad-Eye]

A ship is travelling north with a wind speed of 12 kmph relative to the water.
the water is flowing at 4 kmph in an easterly direction relative to the shore.
Determine the velocity of the ship relative to the shore.

 

[confused123]

one complete cycle is 360 deg. so half a wave will be 180 deg. if you start second wave at half point of the first one, you create a phse difference of 180. a quarter you get 90 deg. a thisrd of the quarter and you get 30 deg phase difference. If you still don't get it ask me and I will explain with figures.

kindly explain with figures.

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w10_qp_23.pdf
6 ii) how to calculate the phase angle difference?
6 ii b) how is the ration of intensities 32?

Q.4 c) how to calculate acceleration from the graph?

7 b iii

 

[SuperGirl123]

Need help with Q2.

http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_w08_qp_2.pdf

Attempted this, looked at the mark scheme and I'd done it all wrong.

In the first part I did v2 = 2as. a = 9.81. s = 29.3m. The mark scheme says a = 0.85 and s = 12.8m.
They're asking for the speed BEFORE the brakes are applied so why do we need to use the values for when the car is skidding/decelerating?

Hope I'm making sense.

 

[leosco1995]

g http://www.xtremepapers.com/paper...and AS Level/Physics (9702)/9702_s04_qp_2.pdf
Q8 (c)

How do you solve it?

 

[littlecloud11]

g http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_2.pdf
Q8 (c)

How do you solve it?

when the voltmeter has a resistance of 7800 ohm, the combined resistance in the parallel combination becomes (7800+7800)/ 2 = 3900 ohm ; as resistor R also has a resistance of 7800 ohm.
The thermistor has a resistance of 3900 ohm same as the total parallel combination , so the emf is divided equally between resistor R+ voltmeter and the thermistor. i.e. the emf is 1.5/2= .75 across each component.