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After an approaching ambulance passes a stationary observer what does the frequency of the sound of the siren heard by the observer appear to do?
The frequency of the sound of the siren appears to decrease as the ambulance moves away from the observer. This is due to the Doppler effect, which causes a shift in frequency as the source of the sound moves relative to the observer.
When a wave passes from a less dense medium to a more dense medium what might change?
When a wave passes from a less dense medium to a more dense medium, its speed decreases while its frequency remains unchanged. Additionally, the wave may also experience refraction, causing it to change direction.
How would you friend describe your relative motion as he passes you?
My friend would say that as he passes me, he sees me moving in the opposite direction relative to him. He would also observe a change in the distance between us as he moves ahead of me.
Will stars moving away from earth have a greater frequency?
They should seem to have a lower frequency due to the Doppler effect. The same as when an ambulance passes, the siren seems to go down in pitch because the source is moving away from you, so the time it takes each pulse of the siren to reach you is perceived to be longer.
What is the name of the effect the causes the pitch of an ambulance siren to change as it passes you?
The Doppler effect
Which is true of the Doppler affect?
The Doppler effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It causes a shift in frequency when the source of the wave and the observer are moving towards or away from each other. This effect is commonly observed with sound waves, such as the change in pitch of a siren as an ambulance passes by.
When a wave passes froma less dense medium to a more dense medium the may change?
When a wave passes from a less dense medium to a more dense medium, it generally slows down and changes direction. This change in speed and direction is called refraction. The wave may also experience a change in wavelength and frequency.
If an emergency vehicle passes you in traffic just as it passes you the pitch of the siren changes. This is because?
frequency.
You are in a car going 70 kmh and another car passes you going in the opposite direction at 70 kmh. do both cars have the same velocity?
No. Velocity is a vector, so it has both a magnitude and a direction. If the velocity of your car was heading in the positive direction, then the other car is moving in the negative direction. The velocities are NOT the same!
How does elecricity travel in wires?
Their are two types of ways electricity passes through wires. DC, which stands for direct current, means that the electrons flow in one direction. AC, which stands for alternating current, means that the electrons flow in one direction, then they switch and flow in the opposite direction.
What happens when a sound source passes by you?
it's frequency increases
Why do you hear a higher pitched sound when an ambulance is moving toward you and a lower sound when an ambulance is moving away from you than you would if you and the ambulance were both at rest?
That's called the "Doppler" effect, named for the scientist who explained it. You're standing still, but the train or ambulance is moving toward you. The horn or siren is going. The sound waves go out in every direction, at the speed of sound (about 750 miles per hour, depending on atmospheric pressure). As the train is moving TOWARD you, the sound waves that it generates are being pushed together, because the train is moving too. We hear the effect as if the frequency of the sound waves is pushed together, increasing the frequency. As the train passes by, we hear the "Doppler shift" to the lower frequency, because how the train is moving AWAY and the sound frequencies are stretched out. Now we hear the sound at a lower frequency. If we carefully analyze the Doppler shift, we can determine; 1. Exactly how fast the train was moving 2. How far away the train was when it passed by. Police use the same thing; you're driving along the highway, and a police officer points his radar gun at your car. The radar gun is precisely calibrated for frequency. The radar waves hit your car and bounce off, and the Doppler-shifted frequency can be used to calculate how fast you were going.
