How Do You Calculate Wave Speed and Frequency in Water and Sound Waves?

[ahrog]

Homework Statement

1. Water waves in a lake travel 4.4m in 1.8s. The period of oscillation is 1.2 s.
a) What is the speed of the water waves?
b) What is the period of the water waves?
2. A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.0m separates a trough and an adjacent crest of the surface waves on the lake. They count 14 crests that pass by the raft in 20s. How fast are the waves moving?
3. a) A tuning fork vibrates 192 times in 1.50 s. What is its frequency?
b) What is it's period?

Homework Equations

v=wavelength x frequency
frequency=1/ T

The Attempt at a Solution

1. a) v=d/t
4.4m/1.8s
=2.4m/s

b) f=1/T
=1/1.2s
=0.83 Hz

2.) v= wf
=(6m)(14 crests/20s)
=4.2m/s

3. a) f=1/T =1/(1.5s/192) = 128Hz
b) T=192vibrations/1.50 seconds
=0.00781 s

I just need someone to check these over, as they are worth a portion of my grade, and I don't want to make stupid mistakes.

 

[Carid]

Question 1b
They ask for a period.

Question 2
Fourteen crests corresponds to how many wavelengths?

 

[thomate1]

Your calculations for 1a and 1b are correct. For 2, you should use the formula v = λf, where λ is the wavelength. You can find the wavelength by dividing the distance between the trough and crest (2.0m) by the number of crests (14). So the correct calculation would be:

v = (2.0m)/(14 crests/20s)
= 2.9m/s

For 3a and 3b, your calculations are correct. Just make sure to include the units in your final answers (Hz for frequency and seconds for period).

Overall, your solutions are correct and well-explained. Good job!