Physics, Chemistry and Biology: Post your doubts here!

[xxxt]

area wont double, it will b multiplied by 4!!!

sorry my mistake i was tring to refer to the fact that diameter doubles...

 

[ZainH]

they dont fit in my brain -.- lol ..

Even after my explanation ? D:

 

[EpicLol]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
Q NO 10 (A ) AND (B) IN THE ABOVE PASTPAPER ATTACHED LINK !!!! PLZ HELP ME ....THNX IN ADVANCE

They have been answered already in this forum topic....but here are the answers...in a) the triangulat yhings will be closer to each other, so their height stays the same but the dist between each of the mountains decreased...
b) U change volts/cm setting and make it twice the volts per cm and time base would stay the same....

Do check with others though.,...

 

[sma786]

Even after my explanation ? D:

oh no, i got it thanks alot, =]

 

[semsemhosam]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s11_qp_31.pdf
Question 7 b i please I need to know how to solve it

use speed = frequency x wavelength

 

[Stormcry72]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s11_qp_31.pdf
Question 7 b i please I need to know how to solve it

speed=frequency*wavelength
substitute and solve

 

[ZainH]

ALRIGHT THEN!
*bang head against desk*
TIME BASE
The time base effects the frequency of the shown wave!
If the time base is 1 second, then it will show the number of waves in 1 second!
If time base is 0.5 seconds it will show the number of waves in 0.5 seconds!
So the smaller the time base the less number of waves which appear/the wider they are. If you had LOTS of waves and they were all squashed, you would increase time base to make it clearer. This also means decreasing time base INCREASES wavelength of shown wave.
If it says time base is 5seconds/cm, it means that each cm represents 5 seconds. So if they ask to find the frequency from this this is what you do:
Find the number of centimeters/blocks for one wave (e.g. 5cm)
Multiply this by the time base (e.g if time base is 0.01second/cm, then that's 0.05cm)
This is the PERIOD the time taken for ONE wave
Frequency = 1/Period, so the frequency is 1/0.05 = 20Hz!
Y-GAIN
The Y-Gain effects the HEIGHT of the shown wave.
The height of the wave shows the voltage of the wave
So if the Y-Gain is 5volts/cm and the amplitude of the wave on the screen is 4cm, then the voltage of the wave is 5*4=20V!

Oh god you genius -.-
I now need to spend the rest of time understanding this..
Thanks alot though, really helpful stuff x)

-EDIT-
Wait, if theres alot of waves squashed up, why would we increase the time base? Suppose there are 10 waves being shown in 1 second.. and we increase the time base to 2 seconds, it'd show us 20 waves right? That'd be more squashed together >.<

 

[AAnsarii]

Plz help because I dont reeally understand that....could u explain it more simplified and elaborated so that idiots like me can understand thx

u need 2 noe dat resistance is directly proportional 2 length: l increases so r increases, & resistance is invrsly proportional 2 area, area decreases, resistance increases.
diameter is halved, so (hope u nderstand dis.) by pie r^2, area will b multiplied by 2^2 = 4. {the 2 is here coz u halved d diameter}


so resistance increases to 4*4, = 16 ohms.

now refer 2 d qn, they have current as 0.3A, so actually the resistance= v/i = 1.8/0.3 = 6 ohms
so 4 d ratio, u do resistance of what u need, the actual 1: resistance of r calculated hypothesis, which assumes original length.
= 6/16 =0.375

hope u understood, i noe im a horrible xplainer, n refer to ms, its v helpful.
all d best

 

[Hamzeh S]

How many S.f round our answers to ?

 

[EpicLol]

u need 2 noe dat resistance is directly proportional 2 length: l increases so r increases, & resistance is invrsly proportional 2 area, area decreases, resistance increases.
diameter is halved, so (hope u nderstand dis.) by pie r^2, area will b multiplied by 2^2 = 4. {the 2 is here coz u halved d diameter}


so resistance increases to 4*4, = 16 ohms.

now refer 2 d qn, they have current as 0.3A, so actually the resistance= v/i = 1.8/0.3 = 6 ohms
so 4 d ratio, u do resistance of what u need, the actual 1: resistance of r calculated hypothesis, which assumes original length.
= 6/16 =0.375

hope u understood, i noe im a horrible xplainer, n refer to ms, its v helpful.
all d best

I understand better now but I have 1 question why is pie r^2 would be 2^2 and 4? why is it 4*4?
I do understand that area decreases and resistance increases....so....plz help sorry if Im annoyinh u

 

[EpicLol]

I understand better now but I have 1 question why is pie r^2 would be 2^2 and 4? why is it 4*4?
I do understand that area decreases and resistance increases....so....plz help sorry if Im annoyinh u

shouldnt it just be like (pie r^2)/2 ? because for getting the area?

 

[MERIHAN]

They have been answered already in this forum topic....but here are the answers...in a) the triangulat yhings will be closer to each other, so their height stays the same but the dist between each of the mountains decreased...
b) U change volts/cm setting and make it twice the volts per cm and time base would stay the same....

Do check with others though.,...

CAN U TELL THE LINK OF THE PAGE WHERE THE ANSWER IS SHARED BCUZ THERE ARE 68 PAGES OF THIS THREAD

 

[EpicLol]

shouldnt it just be like (pie r^2)/2 ? because for getting the area?

oh wait now I get it....I understand why u multiply 4*4....ok thx for the help

 

[Dani222]

HELP ASAP

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf
Variant 2
Question 5b (ii)
Question 11 b. How do you get it?

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
Question 2c
Question 11 b.

 

[EpicLol]

CAN U TELL THE LINK OF THE PAGE WHERE THE ANSWER IS SHARED BCUZ THERE ARE 68 PAGES OF THIS THREAD

exactly why I dont search them for u coz I dont know either ....sry....

 

[Khloud]

Plzzz i need help. What happens to the speed of a skier when his acceleration decreases?

 

[ZainH]

Plzzz i need help. What happens to the speed of a skier when his acceleration decreases?

He slows down.
Lol x)

 

[Z.A.M]

use speed = frequency x wavelength

Well just use the formula speed=frequency*wavelength
If u wana know about part 2 that's a little trick
First find the time taken for the shock wave to travel to the centre of earthquake by using s=d/t
6.0x10^5/2.5x10^3=240sec
Then using the same formula find the time taken for the shock waves to travel to the centre by
6.0x10^5/240=2500
Now to find the time taken to make the warning subtract the two 2500-240=2260

 

[EpicLol]

HELP ASAP

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf
Variant 2
Question 5b (ii)
Question 11 b. How do you get it?

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Physics (0625)/0625_s10_qp_32.pdf
Question 2c
Question 11 b.

10.7/2 = 5.35 for 2c

 

[Moi]

Resistance is directly proportional 2 lenght, inversely prop,. 2 area. when u divide the diameter by 2, area increases by4. so new resistance=4(older resistance)*4= 16 ohms
now in d qn, they say dat I is 0.3, so actual resistance isn't 16, its 1.8/0.3=6 ohms
now d ratio... new resistance of actual lenght/calculated resistance of original length = 6/16 = 0.375.
, ma shaaAllahu la quwwata illa billah.

But why when diameter halfed, area increased by 4 ???
and why you multiplied the old resistance with the area in specific ??