Physics help =)

[Unkownbunny]

hiya, hope you guys can help me. I'm having a little bit of difficulty understanding the following questions

http://www.xtremepapers.me/CIE/Cambridg ... _qp_12.pdf
Q 19, 21

http://www.xtremepapers.me/CIE/Cambridg ... 6_qp_1.pdf
Q 37. i really dont get why its cool

and if you dont mind, can anyone please give me a simple explination of frequency, pitch, amplitude and loudness? i thought the pitch increase with loudness but i think i am mistaken. i get very confused with questions concering them


i would be more than grateful if you can help me =)
thank you in advance xxxxxxxxxxxxxxxxxx

 

[Unkownbunny]

explanation ***

 

[haochen]

frequency : the number of wave passing through a certain point in one second and frequency is directly proportional to pitch
which mean if the frequency increases the pitch increases, if the frequency stay the same the pitch stay the same .
And the easy way to find out the frequency is by looking at the gap between the two point touching the wave on the center line.
the larger the lower frequency znd the samller the higher frequency.

amplitude : it is the distance from the highest of the wave straight down to the center line and amplitude is directly proportional to loudness
which mean if the amplitude increases the loudness increases, if the amplitude stay the same tha loudness stay the same.

answer 19 (first link):
from the graph u can say that the wax is cooling because the graph is going down (melting point is the same as freezing when going down)
A) At X the temp drop more quickly than Z because the line of X is steeper than Z so the statement in the question is not true.
B) At Y the wax is still liquid but it is turning to solid so it is not all solid so the statement in the question is not true.
C) At Y it is when liquid changes to solid (freezing) so the energy will be lost because in solid, molecule have less energy than liquid, so energy is given out so this statemant is true.
D) In Z it isat solid state (u may think it is not moving) but even in solid, molecule vibrate at their fixed point so the statement in the question is not true.
so the answer is C

answer 21 (first link):
like i have said louder mean that it have high amplitude so check P have the distance from the tip to the center more or Q ???
its P and the pitch is the same as frequency so the of P is lower (definition) so it is P
which the answer is A.

answer 37 (second link):
Anode mean positive and it is cool because the one emitting the heat is at the before the cathode so the one that is hot is the cathode not the anode
so the answer is C

hope u get it

 

[Ahmooosh]

okay for question 19 , u should know that when things are changing state , they dont gain / lose any temperature , because all energy supplied is being used to break the bonds , so basically in such graphs , horizontal lines mean change in state....

question 21 , well ... the hight of the wave , aka amplitude tells u how loud / quiet the sound is , and the distance between waves , aka wavelength tells u the pitch , shorter distance means higher pitch , so if they want a loud sound , then look for the tallest waves , low pitch , look for bigger spaces in wavelength

for question 37 , i am not sure , dont have a good explanation so looking for one.

hope it helped

 

[Ahmooosh]

haha , haochen beat me to it ;p

 

[Unkownbunny]

Thank you guys soo much i found that soo helpful !!!!

 

[haochen]

ur welcm

@Ahmooosh yeah just a sec different
and the explanation i wrote is not exactly proper wording because it is hard for u guyz/gurlz to understand so i try to use my own word
in writing them

hope u guyz/gurlz understand

 

[Unkownbunny]

hey guys ! im so sorry but i have one more question !!

http://www.xtremepapers.me/CIE/Cambridg ... 8_qp_1.pdf

Q 24 xxxxxx

 

[mshaheen95]

The focal length of a lens is the distance between the center of the lens and the point of intersection of the two converging rays (IMPORTANT the rays must be parallel before hitting lens)
the opposite is true also... any two diverging rays hitting a lens then becoming parallel must occur from the focal point
here is an image http://cinematographynut.com/lenses.html