Wave Properties
What is the one word I told you to remember for how to define a wave?
Disturbance
A wave has a wavelength of 4 meters and a frequency of 3 Hz.
What is the wave’s speed?
v = fλ
3 Hz × 4 m = 12 m/s
What does an object’s position describe?
Where the object is located compared to a reference point.
A car starts at position 0 meters and travels 15 meters forward. What is its final position?
15 m
What are the three main parts of an atom?
Protons, neutrons, electrons
What does the amplitude of a wave represent?
The amount of energy in the wave (how strong or intense it is).
A wave is traveling at 20 m/s and has a wavelength of 5 meters.
What is its frequency?
f = v ÷ λ
20 m/s ÷ 5 m = 4 Hz
How can you tell if an object is in motion?
If its position changes relative to a reference point.
A person walks 10 meters east, then 4 meters west. What is their final position relative to the starting point?
6 m east
Which part of an atom has a negative charge?
electrons
What does frequency tell us about a wave?
How many waves pass a point in a certain amount of time (usually per second).
A wave has a frequency of 10 Hz and a speed of 30 m/s.
What is its wavelength?
λ = v ÷ f
30 m/s ÷ 10 Hz = 3 m
A student walks 5 meters forward, then 3 meters backward. What is the difference between the student’s distance and displacement?
A runner travels 100 meters in 20 seconds. What is their speed?
Speed = distance ÷ time = 100 ÷ 20 = 5 m/s
An atom has 8 protons and 8 neutrons. What is its atomic mass?
16 (protons + neutrons = 8 + 8)
What is the difference between a transverse wave and a longitudinal wave?
A water wave travels 60 meters in 12 seconds.
What is the wave’s speed, and if the frequency is 2 Hz, what is the wavelength?
Step 1: Find speed
v = distance ÷ time = 60 m ÷ 12 s = 5 m/s
Step 2: Find wavelength
λ = v ÷ f = 5 m/s ÷ 2 Hz = 2.5 m
Two students run the same distance, but one finishes faster. Who has the greater speed, and why?
The student who finishes faster has greater speed because speed is how quickly distance is covered.
A bike moves at a constant velocity of 3 m/s for 12 seconds, starting at position 5 meters. What is its final position?
Final position equals the starting position plus velocity times time.
Final position = 5 + (3 × 12) = 5 + 36 = 41 m
An atom has 11 protons. What is its atomic number?
Atomic number = 11
Why can’t sound travel through space?
Sound needs a medium (matter) to travel through, and space is mostly empty.
A wave travels at a speed of 12 m/s and has a frequency of 4 Hz.
Part A:
What is the wavelength of the wave?
Part B:
If the frequency increases to 6 Hz while the wave speed stays the same, what is the new wavelength?
Part A: 3 m
Part B: 2 m
A car’s motion is shown on a distance vs. time graph as a straight, upward-sloping line. What does this tell you about the car’s motion?
The car is moving at a constant speed (distance increases evenly over time).
A car starts at position 20 meters. It travels forward at 4 m/s for 5 seconds, then turns around and travels backward at 2 m/s for 6 seconds. What is its final position?
Step 1: Forward motion → 4 × 5 = 20 m
New position = 20 + 20 = 40 m
Step 2: Backward motion → 2 × 6 = 12 m
Final position = 40 − 12 = 28 m
An atom has 17 protons, 18 neutrons, and 17 electrons.
Atomic mass = 35 (17 + 18)
The atom is neutral because the number of protons equals the number of electrons