Physics paper 21/ M/J 2009

[1992]

I really need help in Q4. b) a good explanation please.

 

[beacon_of_light]

here it goes...

A few rules to remember...

If two springs are attached in series, total spring constant is (K1 x k2)/(K1 + K2) ((as you find the resistance of two parallel resistors)))...and if two springs are in parallel, total spring constant will be by adding the two spring consatnts...K1 + K2

use this equation, L= Ke ( L is load, K is spring constant and x is extension)
for the first arrangement...
e = L/K

e1(extension for first arrangement) = L/(k/2) = 2L/k = 2e ( since L/K = e ...shown above)

total extension is 2e and spring constant of system is 1/2 K

..It will be easier if you find the spring constant first and then the total extension....

Hope it might have been a good explanation...

 

[Nepalibabu]

Frn,
This is an important topic that is although not in our syllabus but often comes...Very well explained beacon of light..
My teacher told to focus on this topic..it might come once again..

 

[1992]

here it goes...

e1(extension for first arrangement) = L/(k/2) = 2L/k = 2e ( since L/K = e ...shown above)

i dont understand this part . shouldnt it be like this: 2L/k=e
not 2L/k = 2e
I dont know y u put 2e over there.
It was a good explantion but does this formula come in the sillabus?? the one of finding k?? i think i should learn it _D

 

[beacon_of_light]

yeah you should....L/K = e is a general formula that we've used!