PY 131 Conceptual Academy Chapter 19

The pendulum is an example of

All of these. (oscillating, harmonic, and steady motion)

The source of all waves is

something that is vibrating.

If the frequency of a wave is 100 Hz, its period is

1/100 second.

The relationship v = fl applies to

sound, light, and all kinds of waves.

Frank Oppenheimer shows a device that transforms periodic motion to

construction of a sine wave.

An example of a longitudinal wave is

sound

When a source moves faster than the waves it produces, the result is a

bow wave for water or a shock wave for air.

**The cycle per second is a unit of**

wave frequency.

Two waves can pass through each other

unaltered.

As a vibrating source moves away from you, the

wave frequency decreases.

A bow wave results when the vibrating source moves

faster than the wave speed.

The speed of sound is about

767 mph.

If the frequency of a particular wave is 20 Hz, its period is

1/20 second.

What travels in a wave from one location to another is

energy.

The speed of a wave can be found by multiplying its frequency by its

wavelength.

Interference is a phenomenon that occurs primarily in

all kinds of waves.

When a sound source approaches a stationary listener, the listener experiences an increase in sound

frequency.

Compared with the speed of a boat moving across the surface of water, the speed of the bow produced is

less

A shock wave occurs when an aircraft travels

faster than the speed of sound.

What is said of a jet flying faster than the speed of sound?

The jet is supersonic.

In what direction do the vibrations of a transverse wave travel?

at right angles to the direction of wave travel.

How is a bow wave produced?

When a wave source moves faster than the waves it produces.

What happens to the period of a vibrating object if you double the frequency?

The period halves.

A wave travels thirty meters in one second at 60 vibrations per second. What is the frequency?

60 hertz and it travels at 30 m/s.

A simple pendulum swings freely in an elevator at rest. As the elevator accelerates upward, what happens to the frequency of the pendulum's swing?

It increases.

When a sound's frequency is doubled, what is cut in half?

**The wavelength.**

A cork bobs up and down one cycle per second as water waves with a wavelength of two meters pass by. What is the wave speed?

\n **2 m/s**

A kid in a swingset swings back and forth every three seconds. If rather than sitting the kid stands up, what happens to the duration of a full swing cycle?

The duration is shortened.

A wave has a frequency of two hertz. What is its wavelength if its wave speed is six meters per second?

\n **3 m. (6 m/s / 2HZ)**

Coming back from a boat trip, your friend explains that the sea was rough with 4 meter high waves. She probably meant that the amplitude of the waves were

\n **2 m.**

The swing with the highest frequency is the swing with the

shortest period.

What is a wiggle in time?

A vibration.

What is the frequency of an object completing twenty vibrations in ten seconds?

2 hertz.

What is the period of an object that vibrates 100 times in 5 seconds?

\n **None of these choices are correct.**

A mass hanging from a spring moves up and down over a range of one meter in 2 seconds. What is the frequency?

\n **0.5 hertz.**

A wave has a frequency of 10 Hz. What is its period?

0\.1 second.

What is the velocity of a wave that traves six meters in 1 second?

6 m/s (i’m so smart)

Your finger dips repeatedly into a still pond to make a series of waves. What happens to the wavelengths of your waves if your finger dips more frequently?

\n **The wavelength shortens.**

Completing ten vibrations in twenty seconds, an object has what frequency?

**0.5 hertz.**

What is a transverse wave? Then, which of the following is not a transverse wave?

\n **sound**

What does the fequency of a pendulum depend upon?

two of these (mass and length)

What is a common source of wave motion?

Vibrating objects.

How many vibrations per second are associated with a 102-MHz radio wave?

\n **exactly 102,000,000**

Each leg of a running horse behaves somewhat like a pendulum. For a higher swing frequency, where should most of the mass of the leg be concentrated?

In the upper part, nearer the horse's body.

What is the amplitude of a wave traveling one meter in one second with a frequency of one hertz?

**not enough information to say**

When the amplitude of a wave is one meter, what is the total distance of displacement?

2 m.

In what direction do the vibrations of a longitudinal wave travel?

along the direction of wave travel.

What can exhibit the Doppler effect?

\n **All of these choices**

Over time a wave will lose energy as heat and this reduces the wave's

**amplitude.**

How is a wave barrier produced?

When a wave source moves as fast as the waves it produces.

Compared to at sea level, how does a pendulum clock run at the top of a tall mountain?

\n **slower**

You're at an outdoor concert. The wind is blowing toward you from the orchestra. The speed of the music you hear will be

\n **increased.**

What is the frequency of the second hand on an old-fashion clock?

\n **1/60 hertz.**

What happens to the angle of a supersonic jet's V-shaped shock wave as the jet goes even faster?

\n **narrower.**

How do the compressions and rarefactions travel in a longitudinal wave?

the same direction.

A cork bobs up and down two cycles per second as water waves with a wavelength of five meters pass by. What is the wave speed?

10 m/s.

How far does a wave travel during a single period?

one wavelength.

Within a sealed room on top of the tallest mountain a pendulum clock runs

slow.

A cork floating in the water bobs up and down through 2 cycles each second because of some passing water waves. What is the frequency of these waves?

**2 hertz**

A floating leaf oscillates up and down two complete cycles in one second as a water wave passes by. The wave's wavelength is 10 meters. What is the wave's speed? A cork floating in the water bobs up and down through 2 cycles each second because of some passing water waves. If the wavelength is 10 meters, what is the wave speed?

20 m/s

Similar to a transverse wave, a longitudinal wave has

\n **amplitude, frequency, wavelength, and speed.**

What is the period of the second hand on an old-fashioned clock?

\n **60 seconds.**

A boat captain observes waves cresting the anchor chain every five seconds. She also estimates 15 meters between the crests. She then calculates the speed of the water waves to be

**3 m/s**

The wavelength of a radio wave received at 100 MHz is

**3.0 m.**