Help with Physic MCQ, urgent!

[link318]

Sorry to create a new post when there is already one for this.

Can anyone help me with some questions, step by step and explanation?

Q21 Nov08
http://www.xtremepapers.me/CIE/Internat ... 8_qp_1.pdf

Q10 and 13 Jun09
http://www.xtremepapers.me/CIE/Internat ... 9_qp_1.pdf

 

[mrpaudel]

for 21..answer is C..as its total extension is 1.5e ..... here's a key point for these types of question....

when such springs are in parallel as in number A...u have to add the way as u do for resistance.. if there are two springs in parallel the total xtension is e/2...if there are 3..xtension is e/3 and so on...!! and if in series,,jus add...so for C....the total extension is e/2 + e= 1.5e...which is the highest among all!!

 

[mrpaudel]

for june 09 question number 10...the answer is C....coz the mass M will gain double velocity than that of the mass 2m...so x/y=m*(2u)^2/2m*u^2 gives u 2/1 ....

 

[mrpaudel]

i dont know bout the other one..!!