MJ 09 physics help!

[Alayna]

hey
i got stuck in some places
would someone please explain me:

2)d) Using your answer in (c) and information from Fig. 2.2, deduce quantitatively whether
the collision is elastic or inelastic.

according to the marking scheme;
speed of approach = 4.0 m s-1 and
speed of separation = 2.4 m s-1 .............................................. M1
not equal and so inelastic

i dont understand how speed of separation is 2.4??? :S


and no. 4) B) that whole table... can some please explain me how you get those answers?

no. 5) B) how do you do that? i really didnt understand marking schemes method.. :s

no 6. B) 1) i know F = ma
but how do you know the mass of the electron? i thought the mass of an electron was almost negligible :s

yeah, thats all.

i dont mean to sound like a complete retard by asking so many questions.. but i really need help

thanks in advance!

[nid404]

2) d) Not sure. I used the conservation of k.e.

4)b) In series k of each spring adds up like how you add up resistors in parallel. Spring parallel have their ks added up like resistors in series.

So for the first 1 1/k= 1/k + 1/k  resultant k=k/2  F=ke e=F/k/2= 2F/k = 2e

2) K= 2k F=2ke   extension will be 1/2e

3) The k for the 2 springs in parallel added up 2k...this is in series with 1 spring. 1/2k + 1/k=1/K K =2/3k e=3/2e

Hope this is clear

5) there is a formula u need to know

phase difference=( 2pi/ lamda)  X path difference

phase difference = pi [ for destructive interference]
lambda(wavelength) = 2pi/ pi  X path difference.
path difference is S2M - S1M 
find S2M using Pythagoras = root of 802 + 1002
                                                   =128
path difference= 128-100=28
wavelength= 2pi/pi X 28
               =56cm                 
At f= 1KHz wavelength= 0.33m/ 33cm
At f=4kHz   wavelength= 0..0825/8.25cm
wavelength changes from 33cm to 8.25cm
for minima...phase difference should be either one of them pi, 3pi,5pi,7pi [sub them in the eqn]
minima is observed when lambda= 56cm, 18.7cm, 11.2cm, 8cm
which are the 2 values between 33 and 8.25?? 18.7 and 11.2...so only 2 minimas


6) b) Mass of electron is mentioned on the data booklet.

[Alayna]

omg i love you! <3
thank you so so soooo much!
it really helped!