Question

Consider the wave pulses shown in snapshot graphs i-iv below. Each pulse has a time, absolute phase speed, and travel direction given below it.

i)	-3 -2 1 01 2 3 4 5 67 x (m) t = 1 s, 1 m/s ←	ii)	t = 0 s, 2 m/s →
iii)	t = 2 s, 1 m/s →	iv)	t = 3 s, 1 m/s →

1. 
   
2. 
   
3. 
   
4. Select the corresponding history graph A-D given below (or `none') for each snapshot graph. E.g., if the first snapshot has B as a corresponding history graph, the second, C, and the last two, none, enter BCNN. You only have 5 tries.
   

   A)		B)
   C)		D)

Answer 1

ii) does not match any

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i) matches with D

D considers position at x=1

The wave travels in (i) at 1m/s to left. If we consider D, the history is at x=1,where y = 0 and continues as 0 for next two seconds, i.e upto t=3, from t=3 to t=5 it should fall to zero.

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iv) matches with B

in ( iv) wave travels towards right with 1m/s

Reference point in (iv) is x=0 , at t=3 this point was at 0 and earlier 1 sec also at zero but in earlier 2nd  sec should go to y=1 and further 1 sec to y=0.5

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iii) matches with C

in iii) wave travels at 1m/s to right .

In C history is at x =1 m

At x=1 in iii), the value of y at t=2 sec is y=0

in the previou 2secs back it was -1 .