Physics 101 LO

1. HARMONIC WAVES
IN
WHALE SOUNDS

2. WHALES PRODUCE
SOUNDS FOR:
Navigation
Communication
Hunting
THE SPEED OF SOUND
WAVES
In air is ~340m/s
In water is ~1500m/s

3. HEARING RANGE
Humans:
20 ~ 20,000 Hz
Whales:
500 ~ 31,000 Hz

4. QUESTION PART 1
Suppose that you and your
friends were on a boat in the
ocean. You were having a
conversation when a whale
swam by. The wavelength of
the sound produced by you
was approximately 17cm.
Can the whale sense the
sound?

5. Hint 1:
You are given the wavelength of the sound, can
you find the frequency?

6. Hint 1:
You are given the wavelength of the sound, can
you find the frequency?
Hint 2:
Use the equation: v=λf

7. Solution:
 v=λf
 f=
𝑉
𝜆
 =
340𝑚/𝑠
0.17𝑚
 f=2000Hz
 Note that frequency does not change when the
wave moves from one medium to another
 Whales can hear sound frequencies between 500 ~
31,000 Hz
∴ The whale can sense the sound
Rearrange the formula and
solve for f
Use the speed of sound in AIR
because you and your friends
are not underwater
Watch out
for units

8. QUESTION PART 2
Whales use whistles for close-
range communication. The
whistles produced by the
whale have a wave number of
approximately 8π rad/m. Can
you, standing on the boat,
hear the whistles?

9. Hint 1:
You are given the wave number of the sound,
can you find the wavelength?

10. Hint 1:
You are given the wave number of the sound,
can you find the wavelength?
Hint 2:
Use the equation: k=
2𝜋
𝜆

11. Hint 1:
You are given the wave number of the sound,
can you find the wavelength?
Hint 2:
Use the equation: k=
2𝜋
𝜆
Rearrange the equation and solve for λ
λ=
2𝜋
𝑘
=
2𝜋
8𝜋
=0.25m

12. Hint 1:
You are given the wave number of the sound,
can you find the wavelength?
Hint 2:
Use the equation: k=
2𝜋
𝜆
Rearrange the equation and solve for λ
λ=
2𝜋
𝑘
=
2𝜋
8𝜋
=0.25m
Find the frequency of the sound produced by
the whale

13. Solution:
 k=
2𝜋
𝜆
 λ=
2𝜋
𝑘
=
2𝜋
8𝜋
=0.25m
 v=λf
 f=
𝑉
𝜆
=
1500𝑚/𝑠
0.25𝑚
 f=6000Hz
 Note that frequency does not change when the wave
moves from one medium to another
 Humans can hear sound frequencies between 20 ~
20,000 Hz
∴ You will be able to hear the whale whistle 
Use the speed of sound in WATER
because the whale is in water
when it whistled

14. Thank you for Watching

15. WORK CITED
 “Killer Whales Communication & Echolocation.” SeaWorld Parks
& Entertainment. SeaWorld Parks & Entertainment. n.d. Web. 8
Feb. 2015. < http://seaworld.org/animal-info/animal-
infobooks/killer-whale/communication-and-echolocation/>.
 “Killer Whales Senses.” SeaWorld Parks & Entertainment.
SeaWorld Parks & Entertainment. n.d. Web. 8 Feb. 2015. <
http://seaworld.org/animal-info/animal-infobooks/killer-
whale/communication-and-echolocation/>.