• Support PF! Buy your school textbooks, materials and every day products Here!

What is the speed of water waves?

  • Thread starter jai6638
  • Start date
  • #1
263
0
Water waves in a shallow dish are 6 cm long. At one point, the water oscillates up and down at a rate of 4.8 oscillations per second.

A. what is the speed of water waves?


Do i have to just use the formula V=(lambda)(f) = (.06)(4.8) ??


thanks
 
Last edited:

Answers and Replies

  • #2
Doc Al
Mentor
44,943
1,206
That's all there is to it. (Don't forget units.)
 
  • #3
263
0
great thanks.. had another question:

Water waves in a lake travel 4.4 m in 1.8 s. THe period of oscillation is 1.2s.

A. What is the speed of water waves?
b. what is their wavelenght?

Answer A: v=(lambda) / (time)

what would i use as time here? 1.8 s or 1.2 s? why?

thanks
 
  • #4
263
0
also , a sound wave of wavelength .70m and velocity 330m/s is produced for .50s.

A. How many complete waves are emitted in this time interval???
Do i have to calculuate frequency for this?

b. after .50s, how far is the front of the wave from the sourece of the sound?

wont it be .70m as its the wavelength?

thanks
 
  • #5
211
0
jai6638 said:
great thanks.. had another question:

Water waves in a lake travel 4.4 m in 1.8 s. THe period of oscillation is 1.2s.

A. What is the speed of water waves?
b. what is their wavelenght?

Answer A: v=(lambda) / (time)

what would i use as time here? 1.8 s or 1.2 s? why?

thanks
To answer these questions, you first have to calculate the speed of the wave using the simple formula v=dt. (use 4.4m and 1.8s)
To find the period, find the distance the wave travels in 1.2s (using the speed you calculated in A.)
 
  • #6
211
0
jai6638 said:
also , a sound wave of wavelength .70m and velocity 330m/s is produced for .50s.

A. How many complete waves are emitted in this time interval???
Do i have to calculuate frequency for this?

b. after .50s, how far is the front of the wave from the sourece of the sound?

wont it be .70m as its the wavelength?

thanks
To answer A., you have to calculate the frequency.
To answer B., you cannot say the answer is .50s, since the question is not telling you it travels .70m in 0.50s. It is simply telling you that a wave HAVING a wavelength of .70m is "produced" for 0.50s. You just have to use the velocity (330m/s) and the time (0.50s) to calculate the distance it travels in 0.50s.

Always read the problem carefully before attempting to solve it.
 
  • #7
263
0
christinono said:
To answer these questions, you first have to calculate the speed of the wave using the simple formula v=dt. (use 4.4m and 1.8s)
To find the period, find the distance the wave travels in 1.2s (using the speed you calculated in A.)
so i get

V = (4.4)(1.8)= 7.92 m/sec
D = (1.2)(7.92) = 9.5 m
T = 9.5/ ( 1.2) (4.4 ) = 1.8 s !

damn .. im gettin the same T as in the question...?.. what am i doin wrong here

thanks ..

To answer A., you have to calculate the frequency.
To answer B., you cannot say the answer is .50s, since the question is not telling you it travels .70m in 0.50s. It is simply telling you that a wave HAVING a wavelength of .70m is "produced" for 0.50s. You just have to use the velocity (330m/s) and the time (0.50s) to calculate the distance it travels in 0.50s.

Always read the problem carefully before attempting to solve it.

thanks
 
  • #8
263
0
anyone?.....
 
  • #9
211
0
jai6638 said:
so i get

V = (4.4)(1.8)= 7.92 m/sec
D = (1.2)(7.92) = 9.5 m
T = 9.5/ ( 1.2) (4.4 ) = 1.8 s !

damn .. im gettin the same T as in the question...?.. what am i doin wrong here

thanks ..




thanks
I don't quite get what you did...Don't you need to calculate the frequency first?
 
  • #10
263
0
christinono said:
I don't quite get what you did...Don't you need to calculate the frequency first?
a) ok so finding the speed is simply the function of multiplying 4.4 and 1.8 right? ( since v = (lambda)(f) )



B) V = Lambda / Time

Lambda = (V) (time )
= (4.4)(1.8)(1.2)
= 9.5 m

is thta correct?

why would i need to find the frequency?
 
Last edited:
  • #11
211
0
Which question are you talking about?
This one:
Water waves in a lake travel 4.4 m in 1.8 s. THe period of oscillation is 1.2s.

A. What is the speed of water waves?
b. what is their wavelenght?

or this one?:
also , a sound wave of wavelength .70m and velocity 330m/s is produced for .50s.

A. How many complete waves are emitted in this time interval???
 
  • #12
263
0
talkinga bout :

Water waves in a lake travel 4.4 m in 1.8 s. THe period of oscillation is 1.2s.

A. What is the speed of water waves?
b. what is their wavelenght?
 
  • #13
211
0
jai6638 said:
talkinga bout :

Water waves in a lake travel 4.4 m in 1.8 s. THe period of oscillation is 1.2s.

A. What is the speed of water waves?
b. what is their wavelenght?
OK. To find the speed, just use the formula d=vt (d=4.4 and t=1.8). To find the wavelength, just find the distance the wave travels in 1.2 seconds (using the same formula).

Nothing to it! :biggrin:
 
  • #14
263
0
wow! that was stupid of me.... lol...

thanks much :)
 
  • #15
211
0
Physics has its way of seeming so hard at times... :tongue2:
 
  • #16
263
0
christinono said:
Physics has its way of seeming so hard at times... :tongue2:
lol.. so true :)
 
Top