A. Your friend strikes a gong across the room from you. How does the gong make a sound? How does the energy of the sound reach you? Why don't you feel a push of air when you hear the sound? Write three or four sentences to state your answers.

b. Describe the amplitude and frequency of the sound wave for a low, soft note. Identify the characteristic of the sound that is connected to each wave property.

c. Write two or three sentences to define intensity and to state how intensity changes as the distance from the sound is decreased.

d. A sound is transmitted through equal lengths of aluminum and alcohol. In which material does sound travel faster? Write one or two sentences to explain your reasoning.

e. An ambulance with its siren wailing is moving away from an observer. Write two or three sentences to compare the pitch of the sound for the observer with the pitch for the ambulance driver. What is the term used to describe this phenomenon?

(a) Sound waves consists of rarefaction and compression. Sound needs a medium to travel. When a sound travels through a medium, the particles of the air vibrate. There will be compression where the density of air particle is more and rarefaction where there will be less density of air particles.

Sound is a form of energy. It transfers the energy from particle of air to another particle. In this way, a person able to hear the sound.

(b)

The loudness of the sound depends on the amplitude. Higher the amplitude, more will be loudness. Lower the amplitude, lesser will be loudness. The frequency of the sound depends on the pitch. The higher frequency correspondence to high pitch. The lower frequency correspondence to low pitch.

(c)

The intensity of the sound obeys the inverse square law. The intensity of the sound is inversely proportional to square of the distance. As the distance increases the intensity of the sound decreases.

(d)

Sound travels faster in the solid than liquid and gas. A sound travels faster in aluminium than alcohol.

(e)

An ambulance with its siren wailing is moving away from an observer. The difference in the sound of the siren is due to the phenomenon called Doppler effect. This phenomenon is observed when the source is moving with respect to an observer.

When an ambulance approaches then the siren sounds louder and more shrill. But there is a sudden change in the pitch when an ambulance overtakes an observer. There is an apparent increase in the frequency of the wave.

a) The gong elastically deflects and then pushes the molecules of air making sound. Then these molecules push other molecules along the direction of the sound. The energy is small and we can't feel it. However try stand in front of loud low frequency speaker, you will feel it without your ears.

b) Low soft noise: low frequency, low amplitude. frequency is responsible for making bass or high sounds, amplitude makes sound loud or silent.

c) Sound intensity is power per area. Increase distance - area of a spherical sound wave front will increase and intensity will decrease.

d) Speed of sound depends on stiffness and density of a medium,. Without any calculations I'd say that the speed of sound in alcohol is higher.

e) The Doppler effect. For ambulance driver the sound will be higher and louder than for observer cause wavelength will increase, frequency decrease outside the car.