Stucked in a Qn on wave.

  • Thread starter Wen
  • Start date
  • #1
Wen
44
0
A rope of total mass M and length L is suspended vertically.Show that a transverse wave pulse travel in the length of the rope in a time t=2(L/g)^0.5

If i take the distance of any point on the rope ,A, from the lower end to be X.
linear density is M/L
Tension due to the segment of rope below A is MgX/L
velocity =(T/linear mass density)^0.5
=(L^2/Xg)^0.5
if X=L
V= (L/g)^0.5

which is not what is needed to be shown. So where am i wrong?
 

Answers and Replies

  • #2
mukundpa
Homework Helper
524
3
Wen said:

velocity =(T/linear mass density)^0.5
=(L^2/Xg)^0.5


Check your calculations !!! and write [tex] v = dx / dt [/tex]
 
  • #3
quasar987
Science Advisor
Homework Helper
Gold Member
4,783
18
The speed of the wave is not constant. It diminishes as the wave gets closer to the lower end. So to find the time, you have to integrate dx/v.

(And yes, check your calculations :tongue2:)
 

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