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Reply 40
Also for the last part of the last question, when it asks whether the natural freq will increase/decrease, i thought f was proportional to 1/root(m), thus if m increase doesn't f decrease?
ukebert
with regards the atmosphere one, i remember that one kind of raio waves is deflected off the atmosphere from electronics, however couldn't remember whether it was short wave or long wave... and now cannot remember what was in the question.


Shortwave radio bounces off the atmosphere, and it's used for international broadcasting by the bbc etc.
manjidude
Also for the last part of the last question, when it asks whether the natural freq will increase/decrease, i thought f was proportional to 1/root(m), thus if m increase doesn't f decrease?


Yep, that's what I put.
Reply 43
Oh fun, well i think i did enough to get my C so thats good...thanks Question 8!
Reply 44
Schmeevey

couldn't remember that the galaxy was elliptical, I put spherical:rolleyes:


Well it's better than "Blob Galaxy"...

^^^I thought so. So was the thing in the exam short or long, or both?
Reply 45
I totally ****ed up, only ended up answering half the questions, if that....
Reply 46
BA777
Oh fun, well i think i did enough to get my C so thats good...thanks Question 8!

lol, I got to that question and I was like, yes something I actually understand!
Reply 47
^:hugs: at least you've finished your exams:p:

ukebert
Well it's better than "Blob Galaxy"...
^^^I thought so. So was the thing in the exam short or long, or both?

^lol
was wondering wht did people get for the value of the natural frequency of the slab....i got 0.15 hz as i multipled the spring constant for each spring by 4 as there were 4 springs underneath it...
Reply 49
Im finished all my exams!!

Yes it was quite a good exam!

i put resistance would decrease as R = pl/A as if radius gets big so does the Area hence the Resistance gets big!

but it was gd!
Reply 50
The Apprentice
was wondering wht did people get for the value of the natural frequency of the slab....i got 0.15 hz as i multipled the spring constant for each spring by 4 as there were 4 springs underneath it...

I got 4.93Hz
Reply 51
I did the same, except that I divided the mass by 4, since each spring would have only been carrying 1/4 of it. It would have worked out the same, as k/m/4=4k/m

EDIT: although I can't remember what I actually got of course.
Reply 52
manjidude
Also for the last part of the last question, when it asks whether the natural freq will increase/decrease, i thought f was proportional to 1/root(m), thus if m increase doesn't f decrease?


F was proportional to the square root of k/m - increasing the radius of the rod increases the stiffness constant k thus F also increases!

I think I also got 4.93Hz for the frequency in part a. As far as I know increasing the radius decreases the resistance.
TheMole
F was proportional to the square root of k/m - increasing the radius of the rod increases the stiffness constant k thus F also increases!

I think I also got 4.93Hz for the frequency in part a. As far as I know increasing the radius decreases the resistance.


I can't really see that being the case. If k also increases, how do you know it increases proportional to m? if it increases slower than m then the frequency will still decrease.
Reply 54
ILoveComplexNumbers
I can't really see that being the case. If k also increases, how do you know it increases proportional to m? if it increases slower than m then the frequency will still decrease.

But the mass of the slab was constant?

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