sounds and their characteristics

1. The dependence of the speed of sound on the temperature of the propagation medium

2. ·The characteristics of the sound: pitch, loudness, and timbre

3. ·The limited hearing range of frequencies of the ear

4. ·The measuring unit dB

In this lesson you will learn about:

·      

Characteristics of the sound

In this activity you will discover if the sound can be transmitted in empty space

• You will need a device from which the air can be removed and a timer.

• First set up the time to ring in a minute. Put the timer inside the device and let the minute pass. Do you hear the ring? .

• Now remove the air from the device and put again the timer inside the device. Wait till the minute passes. Do you hear the ringing?

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​Activity No 1

Multiple Choice

The sound ……………………………. a medium for propagation.

• needs

• doesn't need

Multiple Choice

The sound ………………………. transmitted in free space.

• can be

• can not be

Multiple Choice

The sound waves are ……………………………. waves.

• mechanical

• electromagnetic

Does the speed of sound depend on the temperature of the propagation medium?

1. Open the simulation: https://www.seilias.gr/images/stories/html5/soundSpeed.html

2. First calculate the speed of sound for the air temperature of 5°C:

•   Set the temperature at 5°C.

• Press the button Μέτρηση.   

• A laptop with two microphones will appear. You can move the microphones to change the distance between them. Set the distance between them to Δx=5m. When you press start, a wave sound is propagating. When it reaches the first microphone the time t₁ is appeared on the laptop’s screen. This is the time needed for the sound to reach the first microphone. When the sound reaches the second microphone the time t₂ is appeared on the laptop’s screen. This is the time needed for the sound to reach the second microphone.

3. With the same way calculate the speed of sound for the air temperature of 20°C and 40°C:

Activity No 2

Multiple Choice

The speed of sound …………………………. on temperature.

·       

• depends

• doesn't depend

Multiple Choice

The speed of sound …………………….…………… with an increase in temperature.

• increases

• decreases

• stays the same

Fill in the Blank

How much is Δt in ms?

,

Fill in the Blank

Calculate now the speed of sound at 5^oC. Do not use decimals

u=

Fill in the Blank

Now write down the speed of sound at 20^oC. Do not use decimals.

u=

Fill in the Blank

Finally calclulate the speed of sound at 40^oC.

u=