| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.30 |
| Score | 0% | 66% |
The pitch of the siren of an approaching ambulance changes as it approaches you. This is an example of which of the following?
refraction |
|
sound radiation |
|
reflection |
|
Doppler effect |
The Doppler effect occurs when the source or listener (or both) of sound waves is moving. If they're moving closer together, the listener perceives the sound with a higher pitch and, when they're moving apart, the listener perceives the sound with a lower pitch.
Which of the following does not represent the freezing point of water?
32°F |
|
0°F |
|
273K |
|
0°C |
The Fahrenheit scale fixes the freezing point of water at 32°F, the Celsuis scale at 0°C, and the Kelvin scale at 273K.
Respiration is the process by which __________ absorb oxygen and eliminate carbon dioxide.
capillaries |
|
bronchioles |
|
blood cells |
|
diaphragms |
The respiratory system manages respiration which is the process by which blood cells absorb oxygen and eliminate carbon dioxide.
Small rocks shed by asteroids and comets that reach the earth are called:
meteoroids |
|
meteorites |
|
shooting stars |
|
meteors |
Smaller rocks shed by asteroids and comets are called meteoroids. When these rocks reach Earth's atmosphere, they burn up in the mesosphere and become meteors. If a meteor manages to reach the Earth, it is called a meteorite.
Saturated fats can __________ LDL ("bad") cholesterol while unsaturated fats can __________ it.
decrease, raise |
|
raise, decrease |
|
decrease, stabilize |
|
stabilize, raise |
Saturated fats can raise LDL ("bad") cholesterol while unsaturated fats can decrease it.