Author Topic: physics!!  (Read 6504 times)

nid404

  • Guest
Re: physics!!
« Reply #30 on: April 16, 2010, 08:32:47 am »
Sir can u do a video on wave formation please....like for the 25th question... :-\

thank you

Amr Fouad

  • Guest
Re: physics!!
« Reply #31 on: April 16, 2010, 10:49:54 am »
5 minutes nid..

nid404

  • Guest
Re: physics!!
« Reply #32 on: April 16, 2010, 10:59:34 am »
5 minutes nid..

yaa sure...U knw i don't favour physics ::)

Amr Fouad

  • Guest
Re: physics!!
« Reply #33 on: April 16, 2010, 11:14:47 am »
scanning q. 13 lol

nid404

  • Guest
Re: physics!!
« Reply #34 on: April 16, 2010, 11:16:00 am »

Amr Fouad

  • Guest
Re: physics!!
« Reply #35 on: April 16, 2010, 11:19:33 am »
now for question 25...

we both know that P is moving downwards..so the only possible answer is A..

If u cudnt imagine it, get a rope, and start making waves..u will find that point p is moving downwards..

check out this site:

http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html

nid404

  • Guest
Re: physics!!
« Reply #36 on: April 16, 2010, 11:23:42 am »
now for question 25...

we both know that P is moving downwards..so the only possible answer is A..

If u cudnt imagine it, get a rope, and start making waves..u will find that point p is moving downwards..

check out this site:

http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html

hmm....when they say the wave is travelling from the left to the right....it means it's going from Q to P right  ???
mahn i jst can't figure physics...

Amr Fouad

  • Guest
Re: physics!!
« Reply #37 on: April 16, 2010, 11:23:54 am »
question 26:

we know that E is proportional to A^2..or energy is proportional to the sqaure of amplitude, and Enegy is proprtional to surface area..

therefore, when the amplitude is doubled, energy is quadripled, so it is now 4E..

and when Sis halfed, E is halfed, and so the answer is 2E..

Amr Fouad

  • Guest
Re: physics!!
« Reply #38 on: April 16, 2010, 11:25:56 am »
hmm....when they say the wave is travelling from the left to the right....it means it's going from Q to P right  ???
mahn i jst can't figure physics...

lol its alright..but these r waves nid! not just ordinary people walking! lol.

so its not possible to go from P to Q...things must be going up and down.

um sorry i cannt explain more than that..did u check the site i wrote down?  :'(

nid404

  • Guest
Re: physics!!
« Reply #39 on: April 16, 2010, 11:27:54 am »
lol its alright..but these r waves nid! not just ordinary people walking! lol.

so its not possible to go from P to Q...things must be going up and down.

um sorry i cannt explain more than that..did u check the site i wrote down?  :'(

I checked...but i don't figure waves....no problem...i knw what ur trying to say....but the thing is i don't understand the motion....
Thanks for trying tho...:)

I'll wait for astar to get me something on waves..

Amr Fouad

  • Guest
Re: physics!!
« Reply #40 on: April 16, 2010, 11:29:47 am »
Question 13:

I hate my scanner!  >:( >:(

lol..anyways..u must draw the whole system first..

Just after 0.5 metres from the pivot, put the 50 N force..Sine the rod is uniform, u must place its weight at the middle..which is 1.5 metres from either sides..

Then, u take moments about the pivot:

Wx1  =  50x 0.5

therefore, W=25 N..

got that?

nid404

  • Guest
Re: physics!!
« Reply #41 on: April 16, 2010, 11:35:49 am »
Question 13:

I hate my scanner!  >:( >:(

lol..anyways..u must draw the whole system first..

Just after 0.5 metres from the pivot, put the 50 N force..Sine the rod is uniform, u must place its weight at the middle..which is 1.5 metres from either sides..

Then, u take moments about the pivot:

Wx1  =  50x 0.5

therefore, W=25 N..

got that?

Yup totally....stupid me  ::)
thanks

Amr Fouad

  • Guest
Re: physics!!
« Reply #42 on: April 16, 2010, 11:36:56 am »
Yup totally....stupid me  ::)
thanks

lol anytime..

wut about q. 26? u got it?

nid404

  • Guest
Re: physics!!
« Reply #43 on: April 16, 2010, 01:00:31 pm »
Im getting 4E as the answer...but it's 2E  :-\ :-\

Amr Fouad

  • Guest
Re: physics!!
« Reply #44 on: April 16, 2010, 01:03:39 pm »
question 26:

we know that E is proportional to A^2..or energy is proportional to the sqaure of amplitude, and Enegy is proprtional to surface area..

therefore, when the amplitude is doubled, energy is quadripled, so it is now 4E..

and when Sis halfed, E is halfed, and so the answer is 2E..

still...?