Physics: Post your doubts here!

[forest822]

Can anyone explain why it is not appropriate to use the Young Modulus to determine the extension when the braking force is applied? Thank You.

 

[eliyeap]

Explain, in terms of the air molecules, why the pressure at the top of a mountain is less
than at sea level ?

Because the density of the air varies. As you go up the mountain, the air gets thinner meaning the no. of air molecules decreases. For pressure, the air molecules collide with one another as well as with the wall of the container. When they collide they experience a change in momentum which in turns produces a force. Pressure is given by the average of this combine collective forces. Hence, the lower the no. of molecules the lower the pressure.

 

[eliyeap]

View attachment 53300 can somebody explain how is the answer for C : 7.4?​

Weight - F=ma
(2.3*9.81) - (0.042* 12^2)= 2.3(a)
23-6.048=2.3(a)
a=7.4 ms^-2

Basically the weight of the object is pulling it downwards while the friction is acting upwards. If the weight is more than the friction then you get an acceleration. Hope you get it!

 

[eliyeap]

Can anyone explain why it is not appropriate to use the Young Modulus to determine the extension when the braking force is applied? Thank You.

Because at the breaking force, the extension is no longer proportional to the force applied, that is hooke's law is no longer obeyed.

 

[princess Anu]

J 2012/22 Q6b
The Examiner report says,' many omitted the adjustments to obtain resonance' :/ I don't get it what is resonance & how do we obtain a reading for it??
Please HELP

 

[The Chill Master]

M/J/2002/P4
Q4 (b) and (c) part can anyone explain?

 

[DESTROYER1198]

does anyone know any good physics revision notes

 

[amal sharkawi]

Can anyone answer this plz??

 

[forest822]

Because at the breaking force, the extension is no longer proportional to the force applied, that is hooke's law is no longer obeyed.

Thank your for the solution. How's Hooke law is related to Young Modulus? Thank You.

 

[Furqan Azam]

Whenever I do a vector question, I stuck on it. Latest one is from Nov 2014. It will be nice if someone can draw the diagrams of Q`1 c i, ii. Thanks.

 

[Xylferion]

Whenever I do a vector question, I stuck on it. Latest one is from Nov 2014. It will be nice if someone can draw the diagrams of Q`1 c i, ii. Thanks.

Look for my post here: https://www.xtremepapers.com/commun...st-your-doubts-here.9860/page-658#post-899092

 

[princess Anu]

is this correct?!

 

[Sarosh Jameel]

Can someone plz help me to derive pressure=density*gravity*height !!!

 

[eliyeap]

Thank your for the solution. How's Hooke law is related to Young Modulus? Thank You.

Young modulus is the gradient for the graph of stress against strain. Normally, when we measure the Young Modulus we take it from the proportional limit, that is the straight line part of the graph. This straight line part denotes the max load for which hooke's law is obeyed and is also the place where elastic deformation occurs. I hope that answers your question! Maybe you should look at the graph for ductile materials for a better understanding.

 

[qwertypoiu]

Can someone plz help me to derive pressure=density*gravity*height !!!

Pressure = force / area = mass * acceleration / (volume / height) = (mass / volume) * acceleration * height = density * gravity * height

 

[Mahnoorfatima]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9702 - Physics/9702_w08_qp_2.pdf
Question 6 part bi, the ER says that describe what will be seen as a result of diffraction of water waves. What do I write in that?
And bii? question 7 a?and bii? And 8 c as well! Anyone PLEASE!

 

[Mahnoorfatima]

http://studyguide.pk/Past Papers/CIE/International A And AS Level/9702 - Physics/9702_s09_qp_2.pdf
1st variant question 5 part b??
2nd variant question 5 part c? How are we supposed to know such type of answers? :/ AND question 7 part a? SOMEONE, PLEASE.

 

[DESTROYER1198]

does anyone know any good physics notes

 

[amal sharkawi]

Can anyone help ???
Plz answer this question

 

[The Chill Master]

Can anyone just explain me how to get amplitude?
20% K.E is lost so left is 80% that means 12 but I can't understand anything further than that.