Standing Waves Basic Calculations

Sketch A shows two identical pulses traveling in opposite directions along a string, each with a speed of 1.0 cm/s. After 4.0 s, the string will look like which of the other sketches?

• 1

• 2

• 3

• 4

• 5

Tags

NGSS.HS-PS4-1

Why does your voice change pitch when you speak after inhaling the contents of a helium-filled balloon?

• The helium decreases the effective length of your vocal cords, so their fundamental frequency is increased

• The helium increases the stiffness of your vocal cords, so their fundamental frequency is increased.

• The speed of sound in helium is higher than the speed of sound in air, so the fundamental frequency of your throat and mouth cavity is increased.

• The speed of sound in helium is lower than the speed of sound in air, so the frequency of the sound released into the air is increased.

• Helium is a lighter gas than air, so the resulting buoyancy force causes the pitch to rise.

The figure represents a string of length L, fixed at both ends, vibrating in several harmonics. Which string shows the 4th harmonic?

• A

• B

• C

• D

• E

Tags

NGSS.HS-PS4-1

The figure represents a string of length L, fixed at both ends, vibrating in several harmonics. Which string shows the 3rd harmonic?

• A

• B

• C

• D

• E

Tags

NGSS.HS-PS4-1

The figure shows several modes of vibration of a string fixed at both ends. The mode of vibration that represents the fifth harmonic is

• 1

• 2

• 3

• 4

• None of these is correct.

Tags

NGSS.HS-PS4-1

A stretched string is fixed at points 1 and 5. When it is vibrating at the second harmonic frequency, the nodes of the standing wave are at points

• 1 and 5.

• 1, 3, and 5.

• 1 and 3.

• 2 and 4.

• 1, 2, 3, 4, and 5.

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-5

A stretched string is fixed at points 1 and 5. When it is vibrating in its first harmonic frequency, the nodes are at points

• 1 and 5 only.

• 1, 3, and 5.

• 2 and 4.

• 2, 3, and 4.

• 1, 2, 3, 4, and 5.

Tags

NGSS.HS-PS4-1

Of the sound sources shown, that which is vibrating with its first harmonic is the

• whistle.

• organ pipe.

• vibrating string.

• vibrating rod.

• vibrating spring.

Tags

NGSS.HS-PS4-1

When an organ pipe, which is closed at one end only, vibrates with a frequency that is three times its fundamental (first harmonic) frequency,

• the sound produced travels at three times its former speed.

• the sound produced is its fifth harmonic.

• beats are produced.

• the sound produced has one-third its former wavelength.

• the closed end is a displacement antinode.

Tags

NGSS.HS-PS4-1

The air in a closed organ pipe vibrates as shown. The length of the pipe is 3.0 m. The frequency of vibration is 80 Hz. The speed of sound in the pipe is approximately

• 80 m/s

• 0.16 km/s

• 0.24 km/s

• 0.32 km/s

• 0.96 km/s

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-5