Molecular Physics | Thermodynamics Answers

A
180-Hz
sound travels through pure helium. The wavelength of the sound is measured to be
5.59 m.
What is the speed of sound in helium?

What frequency of sound traveling in air at 20°C has a wavelength equal to
1.7 m,
the average height of a person?

Ultrasound probes can resolve structural details with sizes approximately equal to the wavelength of the ultrasound waves themselves. What is the size of the smallest feature observable in human tissue when examined with
15-MHz
ultrasound? The speed of sound in human tissue is 1,540 m/s.

A sound pulse emitted underwater reflects off a school of fish and is detected at the same place
0.15 s
later (see the figure below). How far away are the fish? (Assume the water temperature is 20°C.)

The sound level measured in a room by a person watching a movie on a home theater system varies from
60 dB
during a quiet part to
90 dB
during a loud part. Approximately how many times louder is the latter sound?

A 3.2 Hz continuous wave travels on a Slinky. If the wavelength is 0.49 m, what is the speed of waves on the Slinky (in m/s)?

Two children stretch a jump rope between them and send wave pulses back and forth on it. The rope is 2.7 m long, its mass is 0.46 kg, and the force exerted on it by the children is 37 N.

(a)
What is the linear mass density of the rope (in kg/m)?



(b)
What is the speed of the waves on the rope (in m/s)?

An audio speaker producing a steady sound at an outdoor concert is 18 ft away from you. If you move to a position where the speaker is 81 ft distant, by what factor will the amplitude of the sound change?
Af
Ai
=

From a cylinder with a pressure of 60 bar and a volume of 40 l, a quantity of gas is withdrawn which, at an air pressure of 1 bar, has a volume of 80 l. Calculate the pressure in the bottle after the gas has been removed, if the temperature during the process remains constant

A 17-kg piece of metal displaces 2.0 L of water when submerged. Find its density.