Download Practice solving for Torque

Name____KEY_______________________Period_________Date____________
The Speed of Sound and Doppler Effect
v = 331 + 0.6T
1.
Why do we see lightning before we hear thunder?
 We see lightning first because light is much faster than sound.
2.
Explain how pressure affects the speed of sound.
 Increased pressure increases the collisions of the air molecules, transferring the
energy faster and increasing the speed of sound.
3.
In which situation does sound travel faster: (a) outside on a winter day, or (b) outside on a
summer day? Why?
 Sound would travel faster on a summer day because the higher temperature
increases the speed of sound.
4.
Does sound travel faster in steel or liquid water?
 Sound is faster in steel than in liquid water.
5.
What is the speed of sound if the air temperature is 35 °C?
 v = 331 + 0.6T = 331 + (0.6)(35 °C) = 352 m/s
6.
If a fire engine moves toward you, does the pitch of its siren increase or decrease?
 If a fire engine moves towards you, the pitch will increase because of the Doppler
effect.
7.
If you hear the pitch of an engine decrease, is the vehicle moving towards or away from
you?
 If an engine’s pitch decreases, the vehicle must be moving away from you.
8.
A paramedic in an ambulance does not experience the Doppler effect of the siren. Why?
 A paramedic would not notice the Doppler effect, because the paramedic would
be moving at the same speed that the sound is being changed.
9.
The Doppler effect is used by astronomers to determine if stars are moving away from or
toward Earth. Red light has a lower frequency than blue light. If light from a star is
shifted to the red does that mean the star is moving toward or away from Earth?
 If a star shows a lower, red frequency, the star must be moving away from
Earth.