Sound Waves and Light

Why can students hear the sirens of emergency vehicles before they see the flashing lights?

• Sound waves travel faster than light waves.

• Light waves are blocked by the walls of the school.

• Sound waves are blocked by the walls of the school.

• Light waves travel faster than sound waves.

What causes the sound wave to travel through the air?

• The light from the vehicle.

• The vibration of air molecules.

• The color of the vehicle.

• The speed of the vehicle.

What is the speed of sound in air at 20°C?

• 343 m/s

• 1,482 m/s

• 3,650 m/s

• 5,100 m/s

Which material has the highest speed of sound according to the table?

• Air

• Water

• Brick

• Aluminum

What is the pitch of the ambulance siren compared to the fire truck siren?

• Lower pitch

• Higher pitch

• Same pitch

• No pitch

Based on the information in Figure 1 and Table 1, which statement best compares a sound wave in a vacuum to a sound wave in air?

• A sound wave in a vacuum travels much faster than a sound wave in air because there are no molecules to slow it down.

• A sound wave in air travels much slower than a sound wave in a vacuum because of the number of molecules in air.

• A sound wave cannot travel in a vacuum because there are no molecules to transfer the energy.

• A sound wave travels at the same speed in a vacuum as a sound wave in air does.

The diagram shows sound and light waves from an emergency vehicle traveling toward a brick wall. Circle the correct bolded answer in each bracket to complete the sentences about how each wave is affected by the brick wall. The sound waves from the siren will [only reflect off; only pass through; pass through and reflect off] the smooth surface of the wall. The light waves from the emergency vehicle will [only reflect off; only pass through; pass through and reflect off] the smooth surface of the wall. Rougher sections of the wall surface will cause the [sound waves; light waves; sound and light waves] from the emergency vehicle to scatter.

• only reflect off; only reflect off; sound waves

• only pass through; only pass through; light waves

• pass through and reflect off; pass through and reflect off; sound and light waves

• only reflect off; pass through and reflect off; sound and light waves

The diagram shows how a sound wave from an emergency vehicle changes as it moves through air and then through a brick wall. Which statement best describes how the amplitude and energy of a sound wave are affected as the wave travels through air and as the wave travels through a brick wall?

• The sound wave has less energy and a larger amplitude when traveling through a brick wall than when traveling through air.

• The sound wave has more energy and a smaller amplitude when traveling through a brick wall than when traveling through air.

• The sound wave has more energy and a larger amplitude when traveling through a brick wall than when traveling through air.

• The sound wave has less energy and a smaller amplitude when traveling through a brick wall than when traveling through air.

Based on Figure 2, which statement best describes how the pitch and the frequency of sound waves are related?

• A. Sound waves with a higher frequency have a higher pitch.

• B. Sound waves with a lower frequency have a higher pitch.

• C. Sound waves with a higher frequency have a lower pitch.

• D. Sound waves with higher and lower frequencies can have the same pitch.

Which evidence from Figure 2 best supports the answer to Part A?

• A. The ambulance sound waves have fewer waves and a longer wavelength.

• B. The fire truck sound waves have fewer waves and a shorter wavelength.

• C. The ambulance sound waves have more waves and a shorter wavelength.

• D. The fire truck sound waves have more waves and a longer wavelength.