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ALL CIE PHYSICS DOUBTS HERE !!!

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Deadly_king:

--- Quote from: Ghost Of Highbury~ on October 10, 2010, 12:12:46 pm ---One doubt, which point have u considered?

--- End quote ---
Height x above the ground.

It will be 2x for the left limb but x in the right one. Got me?

ruby92:

--- Quote from: ashish on October 10, 2010, 08:00:25 am ---Keplers law T^2 is direcly proportional to R^3

therefore T^2/R^3 = constant

(27.4*24*60*60)^2 / (3.84*10^8)^3 =9.8977*10^-14

let the period be T

T^2 / R^3 = 9.8977*10^-14
T^2 = (9.8977*10^-14)* (6.4*10^6)^3
T = 5093.74 sec
T=1h24min

is that right?

--- End quote ---
Thanks:)

ruby92:
Physics A2 oct/nov 2008 paper 4 q 1aiii
why is it that the normal reaction force=force of gravity - centerpital force.
shouldnt it be plus?

Also m/j 2007 paper 4 q1 bi

Ghost Of Highbury:
i need help in this question

The load on each of the arrangements is L.
For each arrangement , complete the table by determining
(i) the total extension in terms of e,
(ii) the spring constant in terms of k.

Deadly_king:

--- Quote from: Ghost Of Highbury~ on October 10, 2010, 04:54:51 pm ---i need help in this question

The load on each of the arrangements is L.
For each arrangement , complete the table by determining
(i) the total extension in terms of e,
(ii) the spring constant in terms of k.

--- End quote ---

Hmm......Ashish......your spring constants are ok. But am afraid the extensions are not  :-[

Anyway dude, you should know that for spring constant,
When springs are in parallel, their net spring constants are added together. ( Same as for a capacitor and opposite to that of resistors)

When they are in series they are calculated as shown KR = [1/k + 1/k]-1 or 1/KR = 1/k + 1/k

For extension,
When in series, net extension is the sum of the extension of each spring.
When in parallel, it is calculated as shown eR = [1/e + 1/e]-1 or 1/eR = 1/e + 1/e

Let's back to the question now :
1. Total extension will be the sum of extension by each springs when they are connected in series. Each spring extends by e
Hence total extension will be 2e
Spring constant will be [1/k + 1/k]-1 = k/2

2. Since the two springs are connected in parallel, total extension will be e/2 and net spring constant will be 2k
eR = [1/e + 1/e]-1 = e/2
KR = k + k = 2k

3. Total extension : 3e/2
Net spring constant : 2k/3
Use the values you obtained in part(ii)
Total extension = e/2 + e = 3e/2
For the two springs in parallel, net spring constant will be 2k. Hence spring constant of the whole system will be [1/2k + 1/k]-1 = 2k/3

NOTE : kR and eR are the resultant spring constants and resultant extensions respectively.

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