Question 1

Which of the following best describes the difference between constructive and destructive interference in sound waves?

Accepted Answer

Constructive interference occurs when two waves meet in phase, increasing amplitude, while destructive interference occurs when two waves meet out of phase, reducing amplitude.

Question 2

A sound wave travels through air at a speed of $$v = 343\ \mathrm{m/s}. If $$the frequency of the sound is $$f = 686\ \mathrm{Hz}$$, what is its wavelength?

Accepted Answer

$$\lambda = 0.5\ \mathrm{m}$$

Question 3

Which of the following statements about density is correct?

Accepted Answer

Density is defined as mass per unit volume, $$\rho = \dfrac{m}{V}.$$

Question 4

A patient undergoes an ultrasound scan. The frequency of the ultrasound is $$2\ \mathrm{MHz}$$ and the speed of sound in tissue is $$1540\ \mathrm{m/s}. $$What is the wavelength of the ultrasound in tissue?

Accepted Answer

$$\lambda = 0.00077\ \mathrm{m}$$

Question 5

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have free electrons that can move easily throughout the lattice.

Question 6

A wave on a string has a frequency of $$f = 50\ \mathrm{Hz}$$ and a wavelength of $$\lambda = 2\ \mathrm{m}. $$What is the speed of the wave?

Accepted Answer

$$v = 100\ \mathrm{m/s}$$

Question 7

Which of the following is NOT a subatomic particle found in the nucleus of an atom?

Accepted Answer

Electron

Question 8

A light wave passes from air ($$n = 1.00) $$into water ($$n = 1.33). $$What happens to its speed?

Accepted Answer

The speed decreases because $$v = \dfrac{c}{n}.$$

Question 9

Which of the following best describes the relationship between period ($$T) $$and frequency ($$f) of a $$wave?

Accepted Answer

$$T = \dfrac{1}{f}$$

Question 10

A car horn emits a sound at $$500\ \mathrm{Hz}. If $$the car moves toward a stationary observer at $$30\ \mathrm{m/s} ($$speed of sound is $$340\ \mathrm{m/s}$$), what frequency does the observer hear? (Use the Doppler effect: $$f' = f \dfrac{v + v_o}{v - v_s}$$, with $$v_o = 0$$ and $$v_s$$ toward observer.)

Accepted Answer

$$f' = 547\ \mathrm{Hz}$$

Question 11

Which of the following statements about longitudinal waves is correct?

Accepted Answer

The oscillations are parallel to the direction of wave propagation.

Question 12

Which of the following best describes the law of reflection?

Accepted Answer

The angle of incidence equals the angle of reflection.

Question 13

A block of wood floats in water with $$60\% of $$its volume submerged. What is the density of the wood if the density of water is $$1000\ \mathrm{kg/m^3$}$$?

Accepted Answer

$$600\ \mathrm{kg/m^3$}$$

Question 14

Which of the following is a correct statement about the speed of light in different media?

Accepted Answer

The speed of light is highest in a vacuum and decreases in denser media.

Question 15

Which of the following best describes the difference between atoms and molecules?

Accepted Answer

Atoms are single units of elements, while molecules are combinations of two or more atoms bonded together.

Question 16

A person shouts across a canyon and hears an echo $$2.0\ \mathrm{s}$$ later. If the speed of sound is $$340\ \mathrm{m/s}$$, how wide is the canyon?

Accepted Answer

$$340\ \mathrm{m}$$

Question 17

Which of the following is true about the relationship between energy and amplitude in a wave?

Accepted Answer

The energy carried by a wave is proportional to the square of its amplitude.

Question 18

Which of the following best describes the difference between protons and neutrons?

Accepted Answer

Protons are positively charged, while neutrons have no charge.

Question 19

A laser pointer emits light with a wavelength of $$650\ \mathrm{nm}. $$What is the frequency of this light? (Speed of light $$c = 3.0 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$4.6 	imes 10$$^{14}$$\ \mathrm{Hz}$$

Question 20

Which of the following best explains why sound cannot travel through a vacuum?

Accepted Answer

Sound requires a medium (solid, liquid, or gas) to propagate.

Exam 2 Study Guide: Chapters 11, 12, 19, 20 (Atomic Nature of Matter, Solids, Vibrations and Waves, Sound)

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