Wave Problems
(w/study guide and Mythbusters video questions)
10 pts. pp. 1-2, 4 due _______ , p. 3 optional
Name: _______________________________Hour:____
Show all of you work and use the GUE (given, unknown, equation format) where necessary.
1. a. Find the speed of a wave if it has a frequency of 280 Hz and a wavelength of 2 meters. (ans. 560 m/s)
b. How long will it take that wave in part a. to travel one mile? (ans. 2.87 sec.)
c. What is the period of that wave? (ans. 0.0036 sec. )
2. A typical light wave has a wavelength of 580 nm. (1 nm = 10-9 m) Calculate the frequency of that wave.
(ans. 5.17 x 1014 Hz, Hint: You know the speed of light, λ= 580 x 10-9 m, and use parenthesis when u divide.)
3. A sound wave produce by a clock chime is heard 515 meters away 1.5 seconds later. The period of the sound wave
is 0.00229 second. What is the wavelength of the sound wave? (ans. 0.79 m, Hint: use T=1/f to get f. Then use v=∆x/∆t to
get v, then use v=f λ )
4. A typical sound wave might have a frequency of 133 Hz and a wavelength of 2.5 meters. How long would it take
for you to hear the sound if you were 50 meters away from the source of it? (ans. 0.15 sec., Hint use v=f λ to get v. Then
use v=∆x/∆t to get ∆t.)
5. The speed of sound in sea water is 1,530 m/s. A sonar signal is sent straight down from a ship at a point just below
the water’s surface, and 1.80 seconds later the reflected signal is detected. How deep is the ocean beneath the
ship? (ans. 1,377 m) (Hint- the signal travels at a constant speed so that tells you what equation to use. It also has to
travel down and back up. So you’ll need to cut your answer in half to get just the depth.)
6.
a. Calculate the period of a wave from 101.3 FM- KDWB. (ans. 9.87 x 10-9 s)
b.
Calculate the wavelength of the signal from KDWB. (ans. 2.96 m, Hint: Radio waves travel at the speed
of light and make sure to covert the frequency to Hertz.)
c.
Calculate the wavelength of the signal from 1440 AM. (ans. 208.3 m, Hint: Make sure to convert the
frequency to Hertz.)
7. Explain why FM radio stations generally come in better than AM stations.
ANSWER: (since you might not get to this one during class work time)
In order to hear a radio station, you need to pick up the entire wavelength. FM radio stations have
shorter wavelengths, so it is easier for them to get various places.
8. Explain why baseball bats have a “sweet spot.” Include a sketch. See your notes.
9. Show how we got the wave speed equation. (It’s in your Wave Notes.)
10. When you watch a fireworks display do you see or hear the fireworks first and why?
Waves Vocabulary Optional Study Guide You do not have to fill this page out.
**On your quiz, you will be given the definition and you will fill in the word. There’s NO WORD BANK.**
wave- a transfer of ________ from one point to another w/no transfer of _________
medium- the _________________through which a wave travels
transverse wave- a wave whose particles vibrate ________________to the direction of motion of the wave
longitudinal wave- a wave whose particles vibrate ________________to the direction of motion of the wave
crest- the ______ point of a transverse wave
trough- the ______ point of a transverse wave
compression- the area of _________ concentration in a longitudinal wave
rarefaction- the area of _________ concentration in a longitudinal wave
wavelength- (letter for it: ______)- the distance from one part of a wave until it ____________
amplitude- the ___________ of the wave
frequency-(unit: _______________)- the ____________ of waves that pass a given point each _______________
Humans can hear sounds that have frequencies from ____ Hz to __________Hz.
The higher the frequency the higher the ___________ of the sound.
period- how _________ it takes a wave to pass a given point, measured in ___________
superposition- the combination of __________ ____________________ ______________
constructive interference-when the __________ parts of two waves meet and ________ to make a ________ wave
destructive interference-when _____________ parts of two waves meet and ________ to make a _________ wave
complete destructive interference- when two waves meet and _________________cancel each other out
standing wave- a wave pattern that results when two waves of the same ________________, _______________,
and _________________ travel in opposite directions and _____________.
node- a point on a standing wave that is ____________________
antinode- a point on a standing wave where the ______________
______________ occurs
The point on a baseball bat where if you hit it there, little or no vibrations occur is known as the ________ ______.
FM stands for ____________________ _______________________.
AM stands for ____________________ _______________________.
Mythbusters- Can a Singer Break Glass?
~ 18 minutes long
You will turn in after the video.
1) Explain the myth that they are testing. (Explain exactly what they are going to do. Don’t just recopy the title.)
2) A crystal glass has a natural resonance. This is the frequency at which it most
efficiently turns __________ __________ into physical __________________.
3) How did they find the wine glasses fundamental frequency?
4) The fundamental frequency did not break the glass. What do you call the other frequencies they could
try? _____________________
5) It was a Mythbusters’ exclusive. When the glass finally did break, what was the frequency __________?
6) What specifically did they prove for the first time?
that an unassisted voice can actually generate the ___________ to break glass
** TURN THIS ASSIGNMENT IN BEFORE YOU LEAVE TODAY.  **