Q1-LESSON 4: SOUND

Q1-LESSON 4: SOUND

by: Catherine Alarba

Multiple Choice

Sound is produced by vibrations which is the ________ movement of objects.

• forward

• backward

• back & forth

• circular

SOUND PRODUCTION

​Sound is produced by VIBRATION which is the back and forth movement of objects.

​

​Examples:

​1. Vibration of vocal cords

​2. Vibration of strings in guitar

Multiple Choice

Sound energy travels in the form of sound wave, a MECHANICAL WAVE. If so, which is true about sound wave?

• Sound wave can travel in the outer space

• Sound wave can only travel in matter

• Sound wave cannot travel in water

• Sound wave cannot travel in solid material

​Sound Energy and Sound Wave

​Sound is a form of energy.

​It can travel in the form of sound wave, a MECHANICAL WAVE--it needs a medium to travel.

​

​Specifically, it is a LONGITUDINAL WAVE where the displacement of the particles is parallel to the direction of wave propagation

Multiple Select

What are the factors that can affect the speed of sound? Choose all that apply.

• Density

• Elasticity

• Mass

• Temperature

​Factors affecting the speed of sound

ELASTICITY- can return to its original form

• ​sound is faster in more elastic material; ex. steel (solid material)

​DENSITY- amount of mass per area or volume of material (for media of the same phase)

• sound is slower in denser objects; ex. Helium (less densed) vs. Air

TEMPERATURE- the average kinetic energy of atoms and molecules in a system

• ​sound travels faster in high temperature

Multiple Choice

In which medium will sound travel fastest?

• Air

• Railway

• Ocean

• Outer Space

Properties of sound

Reflection- bouncing back of wave as it hits a barrier

• ​ex. echo

• ​ex. reverberation-multiple echoes

Refraction- bending of sound due to changing media or temperature

• ​Ex. sound waves undergo refraction as it moves in air from high temperature to low temperature

Multiple Choice

When is the best time to hold a concert so that sound will reach the ground?

• Morning

• Noon

• Afternoon

• Evening

​Speed of sound in air

​Dry air:

at 0°C, sound travels at 331 m/s

​

​

​For every 1°C increase in temperature, there is a 0.6 m/s increase in speed

​

​

EQUATION:

​

​

​

​where:

​ v= velocity

​ T= temperature in °C

Multiple Choice

What is the speed of sound in the air if the temperature is 29 °C?

• 348 m/s

• 348.4 m/s

• 348.8 m/s

• 349 m/s

What is the speed of sound in the air if the temperature is 29 °C?

What is asked: speed of sound

​Given: T= 29°C

​Equation:

​

​

​Solution:

​ v= 331 + (0.6) (29)

​ v= 331 + 17.4

​ v= 348.4 m/s

Multiple Choice

What is the speed of sound in the air if the temperature is 15 °C?

• 320 m/s

• 330 m/s

• 340 m/s

• 350 m/s

Multiple Choice

What is the speed of sound in the air if the temperature is 23 °C?

• 341.8 m/s

• 342.8 m/s

• 343.8 m/s

• 344.8 m/s

Multiple Choice

What is the temperature if the speed of sound is 349 m/s?

• 29 °C

• 30 °C

• 31 °C

• 32°C

What is the temperature if the speed of sound is 349 m/s?

What is asked: Temperature

​Given: v= 349 m/s

​Equation: T= v - 331

​ 0.6

​Solution:

​ T= 349 - 331

​ 0.6

​ T= 18

​ 0.6

​ T= 30 °C

Multiple Choice

What is the temperature if the speed of sound is 353.2 m/s?

• 37 °C

• 38 °C

• 39 °C

• 40 °C