| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 2.74 |
| Score | 0% | 55% |
Which of the following is not a characteristic of the Sun?
is composed of hydrogen and helium |
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makes up over 99% of the mass of the solar system |
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is a yellow dwarf star |
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formed 2.6 billion years ago |
The Sun is a G-type main-sequence star (G2V) but is informally known as a yellow dwarf star. Composed of 73% hydrogen and 25% helium, the hot plasma that makes up the Sun reaches 9,900°F (5,505°C) at the surface. It formed approximately 4.6 billion years ago and makes up 99.86% of the mass in the solar system.
The hottest of Earth's atmospheric layers is which of the following?
troposphere |
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stratosphere |
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mesosphere |
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thermosphere |
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.
Meteoroids, meteors and meteorites are categorized based on which of the following?
their temperature |
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their density |
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their size |
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their location |
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.
Acceleration is the rate of change of velocity per unit of time. Which of these is the formula for acceleration?
\(\vec{a} = { \vec{v} \over t }\) |
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\(\vec{a} = { \Delta \vec{v} \over t }\) |
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\(\vec{a} = { t \over \Delta \vec{v} }\) |
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\(\vec{a} = \Delta \vec{v} t \) |
Acceleration is the rate of change of velocity per unit of time. In physics, the delta symbol (\(\Delta\)) represents change so the formula for acceleration becomes \(\vec{a} = { \Delta \vec{v} \over t }\)
In the food chain, omnivores may be which of the following?
secondary or tertiary consumers |
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primary or tertiary consumers |
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primary or secondary consumers |
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secondary consumers or scavengers |
Secondary or tertiary consumers may be omnivores.