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CIE AS LEVEL PHYSICS MULTIPLE CHOICE DOUTS

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joel:
Can some one explain the answers please...
Especially the last question because E = V/D...

I have attached a file containing the questions.

1. May/June 2002 Question 9 - Correct Answer B
2. May/June 2002 Question 28 - Correct Answer C
3. October/November 2002 Question 11 - Correct Answer A
4. October/November 2002 Question 18 - Correct Answer D
5. October/November 2002 Question 35 - Correct Answer D
6. May/June 2003 Question 5 - Correct Answer C
7. May/June 2003 Question 35 - Correct Answer C

 
 
 

nid404:
in an hour's time

nid404:
1) Momentum and kinetic energy both are conserved

Momentum before collision= mv+ m(-v) = 0

So momentum after collision will also be zerio

Kinetic energy before collision= 1/2 mv2 + 1/2 m (-v)2= mv2
This is conserved since it's an elastic collision.

Hence B

nid404:
2)


there's a formula for such type of question



for destructive interference the phase difference should be

so if you rearrange the eqn (i substituted phase difference as

=

path difference= S2X-S1X

so you get

=

nid404:
3) elastic collision kinetic energy is conserved.


--- Quote from: ~Ahana~ on May 07, 2010, 09:24:38 pm ---Q11) this is gonna be long...

In an elastic collision...momentum as well as kinetic energy is conserved,,
conservation of momentum
total momentum before collision=total momentum after collision.
mu1+mu2=mv1+mv2

conservation of k.e
1/2mu12+ 1/2mu22= 1/2mv12+1/2mv22

cancel all the halfs first, then cancel all the 'm' terms.

in steps...here's how u do it

m(u1-v1)=m(v2-u2) 1)
m(u12-v12)= m( v22-u22)  2)

since (u12-v12)= (u1-v1)(u1+v1)
     &  ( v22-u22)=(v2-u2)(v2+u2)   

divide the 2nd eqn by the first
m(u12-v12)      m( v22-u22)
---------------------------------= ------------------------------------
m(u1-v1)                                                   m(v2-u2)

m [(u1-v1)(u1+v1)]=[m(v2-u2)(v2+u2)]
-------------------  ------------------
m(u1-v1)                  m(v2-u2)

and then cancelling gives
(u1+v1)=(v2+u2)
or
u1-u2=v2-v1

now coming back to the question.
u1-u2 in this case will be positive because u for the other body is in the opp direction
u1-(-u2)=u1+u2
v2-v1 will be as it...both move in the same direction after collision
so u1+u2=v2-v1




--- End quote ---

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