answer for sound worksheet
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sound, answerTRANSCRIPT
Sound Homework
1. What causes sound?
Vibration of objects
2. How does sound travel from one place to another?
When an object vibrates, it alternately pushes and pulls the air adjacent to it. This
causes the air to form layers of compression and rarefaction. This disturbance is
then passed from particle to particle, causing the compressions to propagate
outwards.
3. Compare the speed of sound in solid, liquid and gas
Sound travel fastest in solid, followed by liquid and slowest in gas.
4. Why can’t sound travel in vacuum?
Sound requires the vibration of particles to propagate and there is no particle in
the vacuum.
5. How can I prove that sound cannot travel in vacuum?
Conduct the bell jar experiment. When air is drawn out of the jar
slowly, the sound of the bell gets softer until it cannot be heard
anymore although the bell is still ringing.
6. What is the relationship between pitch and frequency?
The higher the frequency of vibration, the higher the pitch of the sound. (Pitch is
proportional to frequency)
7. What is the relationship between loudness and amplitude?
The greater the amplitude of vibration, the louder the sound. (Loudness is
proportional to amplitude)
8. How do I determine the speed of sound?
Two persons are stationed at a distance, s, about 1 km apart in an open field.
One of them fires a pistol and the other measure the time interval, t, between seeing the smoke from the pistol and hearing the sound.
Speed of sound = distance / time = s / t
9. What is ultrasound?
Ultrasound is sound wave with a frequency larger than 20 kHz.
10.What is the use of ultrasound?
Any one of the below:
Medical field
Ultrasound waves can be sent into the patient’s body and its reflection will
show an image of the organs or internal tissue.
Engineering
Ultrasound is sent through metal sheets and the signal from the detector on
the other side of the metal will determine if the sheets are too thin or thick and
sent signal to adjust the rollers to give the desired thickness.
Cleaning objects
Ultrasound causes liquid particles to vibrate at high frequency and help to
remove dirt trapped in the jewellery or spectacles that is submerged in the
liquid bath.
Sonar
Ultrasound is sent under water and the time taken for the reflected wave to
reach the detector that is on the water surface will give the distance of the
underwater object.