Waves in Motion (Physics) for Grade 7 Students

2. WHICH AMONG THE THREE IS NOT
A WAVE?1
2
3
ALL ARE
EXAMPLES OF
WAVES.

3. TYPES OF WAVES
ACCORDING TO
PROPAGATION
Mr. Aaron F. San Jose
Science & Technology 7

4. WHAT IS
A WAVE?

5. WAVE
•A TRAVELLING DISTURBANCE THAT CARRIES
ENERGY FROM PLACE TO PLACE WITH OR
WITHOUT A MEDIUM.

6. VOCABULARY
•DISTURBANCE
•MEDIUM

7. DISTURBANCE

8. MEDIUM the substance
that carries a
wave (or
disturbance)
from one
location to
another.

9. TWO CLASSIFICATIONS OF WAVES
•According to Propagation
-Transverse Waves
-Longitudinal Waves
•According to Medium
-Mechanical Waves
-Electromagnetic Waves

10. TYPES OF WAVES
ACCORDING TO
PROPAGATION

11. TRANSVERSE WAVES
•the movement of the particles of the medium
is perpendicular (at a right angle) to the
direction of propagation of the wave.
•(ex. electromagnetic waves,
rope waves,
ocean waves)

12. PARTS OF TRANSVERSE WAVE
CRES
T
TROUG
H
EQUILIBRIUM
WAVELENGTH
WAVELENGTH
AMPLITUDE

13. LONGITUDINAL WAVES
•Medium moves in the same direction as the
wave’s motion
•(ex. Sound waves, spring, slinky)

15. PARTS OF LONGITUDINAL WAVE
C O M P R E S S I O
N
R A R E F A C T I O
N

16. CHARACTERISTICS
OF WAVES

17. WAVE CHARACTERISTICS
•Wavelength
•Amplitude
•Frequency
•Wave speed

18. 1. WAVELENGTH
•Symbol: λ
•The distance between one point on a wave
and the exact same place on the next wave.

19. 2. AMPLITUDE
•The vertical distance of a wave

20. 3. FREQUENCY
•Number of waves passing through a given
point in one second
•Unit: Hertz (Hz)
•𝑓 =
𝑣
𝜆
•Where:
•f = frequency
•v = wave speed
•Λ = wavelength

21. 3. FREQUENCY
•SAMPLE PROBLEM #1
•A wave has wavelength of 10 m and a
speed of 340 m/s. What is the frequency
of the wave?
• 𝑓 =
𝑣
𝜆
•𝑓 =
340 𝑚/𝑠
10 𝑚
•𝑓 = 𝟑𝟒 𝑯𝒛

22. 3. FREQUENCY (TRY THIS ONE!)
•SAMPLE PROBLEM #2
•The speed of a wave is 65 m/sec. If the
wavelength of the wave is 0.8 meters, what
is the frequency of the wave?
• 𝑓 =
𝑣
𝜆
•𝑓 =
65 𝑚/𝑠
0.8 𝑚
•𝑓 = 𝟖𝟏. 𝟐𝟓 𝑯𝒛

23. 3. FREQUENCY (TRY THIS ONE!)
•SAMPLE PROBLEM #3
•A wave traveling at 230 m/sec has a
wavelength of 2.1 meters. What is the
frequency of this wave?
• 𝑓 =
𝑣
𝜆
•𝑓 =
230 𝑚/𝑠
2.1 𝑚
•𝑓 = 𝟏𝟎𝟗. 𝟓𝟐 𝑯𝒛

24. 4. WAVE SPEED
•Distance travelled by a given point of a
wave, such as crest or trough, in a given
interval
•Unit: m/s
•𝑣 = 𝑓 x 𝜆
•Where:
•f = frequency
•v = wave speed
•Λ = wavelength

25. 4. WAVE SPEED
•SAMPLE PROBLEM #1
•A wave has frequency of 50 Hz and a
wavelength of 10 m. What is the speed of
the wave?
•𝑣 = 𝑓 x 𝜆
•𝑣 = 50 Hz x10 m
•𝑣 = 500 m/s

26. 4. WAVE SPEED (TRY THIS ONE!)
•SAMPLE PROBLEM #2
•A wave with a frequency of 14 Hz has a
wavelength of 3 meters. At what speed
will this wave travel?
•𝑣 = 𝑓 x 𝜆
•𝑣 = 14 Hz x 3 m
•𝑣 = 42 m/s

27. THOUGHTO
PONDER

28. ISRAEL UK PORTUGAL
GREECE SPAIN
SWEDEN

29. SEATWORK:
1. A wave has a wavelength of 125 meters
is moving at a speed of 20 m/s. What is its
frequency?
2. A wave has a frequency of 46 Hz and a
wavelength of 1.7 meters. What is the
speed of this wave?

30. SEATWORK:
•A wave has a wavelength of 125 meters
is moving at a speed of 20 m/s. What is
its frequency?
• 𝑓 =
𝑣
𝜆
•𝑓 =
20 𝑚/𝑠
125 𝑚
•𝑓 = 𝟎. 𝟏𝟔 𝑯𝒛

31. SEATWORK
•A wave has a frequency of 46 Hz and a
wavelength of 1.7 meters. What is the
speed of this wave?
•𝑣 = 𝑓 x 𝜆
•𝑣 = 46 Hz x 1.7 m
•𝑣 = 78.2 m/s

32. ASSIGNMENT
•Read pages 244-249 of Science for the
21st Century Learner for preparation of
tomorrow’s lesson.
•Answer the wave problems given by your
teacher

34. WHAT IS A TRANSVERSE WAVE?
•the movement of the particles of the
medium is perpendicular (at a right
angle) to the direction of propagation of
the wave.
•(ex. electromagnetic waves,
rope waves,
ocean waves)

35. WHAT IS A LONGITUDINAL WAVE?
•Medium moves in the same direction as
the wave’s motion
•(ex. Sound waves, spring, slinky)

36. PARTS OF TRANSVERSE WAVE
CRES
T
TROUG
H
EQUILIBRIUM
WAVELENGTH
WAVELENGTH
AMPLITUDE