Practice Pressure Wave in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

A pressure wave is a longitudinal wave made of alternating regions of higher and lower pressure moving through a medium.

Instead of crests and troughs, the medium gets squeezed and spread out as the wave passes.

Showing a random 20 of 50 problems.

Example 1

hard

Sound intensity is given by

I = \Delta P^2 / (2\rho v)

where

\rho

is air density and

v

is sound speed. For

\Delta P = 0.6 \text{ Pa}

\rho = 1.2 \text{ kg/m}^3

v = 340 \text{ m/s}

, find the intensity.

Example 2

medium

A pressure wave is plotted with pressure on the y-axis and position on the x-axis. What single quantity does the x-distance between adjacent peaks represent?

Example 3

easy

Sound at

20^\circ\text{C}

in air travels at about

343 \text{ m/s}

. Does increasing temperature increase or decrease the speed?

Example 4

easy

The distance between a compression and the next rarefaction is

0.25 \text{ m}

. Find the wavelength.

Example 5

easy

In a pressure wave, what are the high-pressure regions called?

Example 6

medium

A microphone records 1200 compressions arriving in 2.0 s. Find the wave's frequency.

Example 7

medium

Two compressions and the rarefaction between them span 0.9 m. What is the wavelength?

Example 8

medium

A sound wave's wavelength is

1.36 \text{ m}

in air (

340 \text{ m/s}

). Find its period.

Example 9

easy

Pressure waves alternate between regions of high and low pressure. What two names label these regions?

Example 10

hard

Two coherent loudspeakers

1.7 \text{ m}

apart emit pure

200 \text{ Hz}

tones in phase (

v = 340 \text{ m/s}

). A listener stands on the perpendicular bisector. Will the speakers' sounds reinforce, cancel, or partially overlap there?

Example 11

medium

Using the same wave

\Delta P = (2 \text{ Pa})\sin(2\pi(680 t - 2x))

, find the wave's speed.

Example 12

medium

A pressure sensor reads atmospheric pressure plus a fluctuation peaking at +2 Pa and dipping to -2 Pa. What is the pressure amplitude of the wave?

Example 13

challenge

A pulse with pressure amplitude

0.4 \text{ Pa}

in air (

\rho = 1.2 \text{ kg/m}^3

v = 340 \text{ m/s}

) spreads as a spherical wave from a point source. Use

I = \Delta P^2/(2\rho v)

at the 1.0 m radius. What is the source's total power (assume isotropic emission)?

Example 14

hard

Two coherent in-phase speakers separated by

0.85 \text{ m}

emit

400 \text{ Hz}

tones (

v = 340 \text{ m/s}

). A listener directly in front of one speaker (so the path difference equals the speaker separation) experiences what type of interference?

Example 15

easy

A sound wave's wavelength in air is

0.10 \text{ m}

and

v = 340 \text{ m/s}

. Find its frequency.

Example 16

easy

A pressure wave's amplitude is

0.5 \text{ Pa}

above atmospheric. What is its peak-to-peak pressure variation?

Example 17

medium

If a sound wave's pressure amplitude doubles, what happens to its frequency?

Example 18

medium

A loudspeaker emits sound at

250 \text{ Hz}

. A pressure probe sits exactly

\lambda/4

from the speaker. What is the phase difference between the speaker's vibration and the pressure at the probe?

Example 19

easy

Can a pressure (sound) wave travel through a vacuum?

Example 20

easy

A sound has period

T = 0.005 \text{ s}

and travels in air at

340 \text{ m/s}

. Find its wavelength.

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Related Concepts

Longitudinal Wave Sound