| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.42 |
| 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?
Doppler effect |
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refraction |
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sound radiation |
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reflection |
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 is not true about mass and weight?
weight is the force exerted on an object by gravity |
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mass is the amount of matter something has |
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weight depends on the location where it is measured |
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mass depends on the location where it is measured |
Mass is the amount of matter something has while weight is the force exerted on an object's mass by gravity. So, although a person's mass doesn't change when going from the Earth to the Moon, their weight will decrease because the force of the Moon's gravity is much less than that of Earth.
These clouds grow upward and can develop into cumulonimbus or thunderstorm clouds.
stratus clouds |
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cumulus clouds |
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cirrus clouds |
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nimbus clouds |
Cumulus clouds are large, puffy, mid-altitude clouds with a flat base and a rounded top. These clouds grow upward and can develop into a cumulonimbus or thunderstorm cloud.
Which of the following represents the largest value?
1 cL |
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1 ML |
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1 mL |
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1 kL |
Mega (M) is 106, kilo (k) is 103, centi (c) is 10-2, milli (m) is 10-3 so 1 ML represents the largest value.
The heat from the Sun traveling to Earth is an example of which of the following?
conduction |
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electricity |
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convection |
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radiation |
Radiation occurs when electromagnetic waves transmit heat. An example is the heat from the Sun as it travels to Earth.