| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.41 |
| Score | 0% | 68% |
The pitch of the siren of an approaching ambulance changes as it approaches you. This is an example of which of the following?
refraction |
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reflection |
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sound radiation |
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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.
Velocity and displacement are fully described by both a magnitude and a direction. Velocity and displacement are which of the following?
scalar quantities |
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vector quantities |
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composite quantities |
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combinational quantities |
Velocity and displacement are vector quantities which means each is fully described by both a magnitude and a direction. In contrast, scalar quantities are quantities that are fully described by a magnitude only. A variable indicating a vector quantity will often be shown with an arrow symbol: \(\vec{v}\)
As part of digestion, the liver produces bile which breaks down:
protein |
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fat |
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starches |
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sugars |
The liver produces bile which emulsifies (separates) fat.
In cell biology, where does DNA replication take place?
Golgi apparatus |
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cytoplasm |
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mitochondria |
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nucleus |
The cell nucleus contains the genetic material of the cell and is where DNA replication takes place.
The hottest of Earth's atmospheric layers is which of the following?
thermosphere |
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mesosphere |
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stratosphere |
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troposphere |
Temperatures again increase with altitude in the thermosphere which is the hottest (4,530 °F / 2,500 °C) atmospheric layer due to direct exposure to the Sun's radiation. However, the gas in this layer is highly diluted so even though the atoms of gas may be very high in temperature, there are too few of them to effectively transfer much heat.