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Physics CIE help

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~ A.F ~:

--- Quote from: nid404 on April 23, 2010, 10:24:14 am ---A.F & astar, help? :-[

--- End quote ---

lol hey nid! :D

give me 5 mins :D

nid404:

--- Quote from: ~ A.F ~ on April 23, 2010, 11:34:41 am ---lol hey nid! :D

give me 5 mins :D

--- End quote ---

sure  :)

~ A.F ~:

--- Quote from: nid404 on April 23, 2010, 08:22:17 am ---M/J 07

Paper 1

Q 20...I really don't understand  :-X

Q23 how?

Q27 Explain again

Q40 Lowest speed would be one with greatest mass right...then how's it C...or is it cuz of the charge??

Thanks


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Q20: W acts downward on X..therefore its tension..now its A or B
        Also, any particle at point Y is pulled downwards, and therefore its under tension(this situation is exactly like the one where steel is beneath the concrete and weight is added..)

Q23: Actually this is A2 physics..lol but nvm :P..

You see..there are rules to memorize (and understand in A2):
* when there is maximum displacement, there is maximum acceleration and zero velocity..I magine a pendul swinging, at the far end there's maximum displacement, right? and also it momentarily stops, as it will move in the opposite direc. next---->therefore, max disp, max acc, zer velocity..

Also a pendulum swing exactly in the midpoint, will have its maximum velocity, where it has zero displacement (at the centre poiny of the system)

Therefore, in this case, point S has max displacement (on crest-amplitude) and so max acceleration..

Q27: You must exclude B and C at first..All arrows in each case point in the same direction, right? whislt a longitudinal wave is one in which compressions and rarefactions occur along the pathway of the wave...

So now its A and D...Again u must exclude D as arrows are pointing in the opposite direct, but this time AWAY from each other..There wouldnt be a wave then, as there wouldnt be a compression(no "squeazing" lol) ..and in D the particles would move AWAY from each other..

So the answer is A....

Q40:
 You cudnt just depend on the mass alone..Its totally wrong..U must use the following equations:

E=qV...where q=charge, V= voltage

at the same time, E= 0.5 x m x v^2...right? Kinetic Energy..

therefore:

qV=0.5 m v^2

v^2= 2qV/m

however, Voltage V is constant..therefore:

v^2 is proportional 2 2q/m

Now u HAVE to substitute values in A, B, C, and D:

A---> m=1. q-1, therefore v= 2q/m

B---> m=4, q=2, therefore v= 2 x 2q/4m= q/m

C---> m=7, q=3, therefore v= 2qx3/7m= 6q/7m

D---> m=9, q=4, therefore v=2x4q/9= 8q/9m

C has the smallest ratio, and so C is the answer..

Tala! lol :P

Was I clear in everything? ::)

nid404:
ohhhhhh!

Thank you so much  :-*

~ A.F ~:

--- Quote from: nid404 on April 23, 2010, 12:04:44 pm ---ohhhhhh!

Thank you so much  :-*

--- End quote ---

lol anytime dear  :)

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