Simple Harmonic Motion
A mass is attached to a spring and allowed to move in simple harmonic motion. If the mass is increased, what will happen to the period?
The period will also increase.
What is being described? "The number of complete cycles per unit time."
Frequency
You are standing on the side of the road when an ambulance approaches you. Does the siren sound higher or lower than if the ambulance was stationary?
Higher pitched.
What is the name of the location on a standing wave where no motion occurs.
Node
Two wave pulses, both upright, approach each other from opposite directions on a rope. When the two overlap, they create a large combined pulse, then separate again. What type of interference is this?
Constructive Interference.
A mass is attached to a string and allowed to swing as a pendulum. If the mass is increased, what will happen to the period of the pendulum?
The period remains the same.
A student looks at a graph of a wave and measures the vertical distance from a crest to a trough. What has the student measured?
You are vacuuming the living room one day next to your sleeping dog. Startled by the sound, your dog runs into the next room. Consider the doppler shift equation. Should you use the top symbol or bottom symbol for this situation?
Bottom symbol as the dog runs away.
A standing wave with 4 nodes and two fixed ends has how many antinodes?
3 antinodes.
Noise canceling headphones use the properties of interference to actually "cancel out" the sounds of the environment. What type of interference do these headphones take advantage of?
Destructive Interference.
The length of the string on a pendulum quadruples. What happens to the period of its swing?
It doubles.
True or false. A swimmer is creating waves in a pool by kicking their feet up and down. If the swimmer doubles the frequency of their kicks, the waves will travel twice as fast.
False. The wavelength will halve, but the speed of the waves will remain the same.
Identify fo in the following problem. "A truck is traveling at 30 m/s when the driver honks its horn. The driver hears a frequency of 500 Hz, while someone driving the opposite direction on the other side of the road hears a frequency of 450 Hz. What is the speed of the car on the other side of the road?"
450 Hz.
A length of string has two fixed ends and a total of 5 nodes. If the string is 10 m long, what is the wavelength of the standing wave.
5 m
When a guitar string is plucked, a pulse is sent down the string. That pulse then reflects off the bridge. Will the reflection be in the same direction as the pulse, or inverted?
Inverted. The bridge is a fixed end.
An unknown mass is attached to a spring with spring constant 50 N/m which oscillates with a period of 2s. What spring constant is needed to make the mass oscillate with a period of 1s?
200 N/m (To halve the period, quadruple k)
Traffic jams can occur when a driver changes lanes suddenly causing the cars behind them to brake. This in turn causes a chain reaction of other drivers braking causing a once steady stream of cars to become a clumpy mess of dense pockets and sparse areas. What type of wave does this pattern most closely resemble?
Longitudinal waves!
Based on the following problem, determine if the drivers are moving toward, or away from each other. "A truck is traveling at 30 m/s when the driver honks its horn. The driver hears a frequency of 500 Hz, while someone driving the opposite direction on the other side of the road hears a frequency of 450 Hz. What is the speed of the car on the other side of the road?"
Must be moving away as the car on the other side of the road hears a lower frequency.
A standing wave with fixed ends has 3 antinodes. If the length of the string is 10 m, what is the wavelength of the wave?
6.67 m
A thick rope is attached to a thin string when a pulse is sent through, starting from the thick end. A reflection occurs at the boundary between the two ropes. Is the reflection upright or inverted, explain.
The reflection is upright as the thin rope acts like a loose end to the thick rope.
A pendulum is set swinging on a mysterious new planet. The pendulum has a length of 50 cm and swings completely back and forth 10 times in 20 seconds. What is the strength of gravity on this planet (in m/s^2)?
4.93 m/s^2
You are standing on a dock next to your 15 ft boat watching waves move by. Assuming you have a stopwatch on you, which of the following could you NOT measure. Wavelength, Period, Frequency, Velocity, Amplitude.
Amplitude. You could not measure the amplitude of the waves without a vertical reference for height.
Answer the following problem: (v = 343 m/s)
"A truck is traveling at 30 m/s when the driver honks its horn. The driver hears a frequency of 500 Hz, while someone driving the opposite direction on the other side of the road hears a frequency of 450 Hz. What is the speed of the car on the other side of the road?"
7.3 m/s
Standing waves can occur in any medium under the right conditions. For example, you can see standing waves in the water in a pool or bathtub, but rarely will you see them in the open ocean. Why not?
No reflections. Standing waves are formed by the interference between waves and reflections.
Of interference, reflection, and transmission, which is most important in the change in the sound of a person's voice when they inhale helium?
Transmission. The sound must pass from the helium medium, to the air, then to your ears.