| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.13 |
| Score | 0% | 63% |
Which of the following is not a medium for sound waves?
vacuum |
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liquid |
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solid |
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none of these is a medium for sound waves |
A vibrating object produces a sound wave that travels outwardly from the object through a medium (any liquid or solid matter). The vibration disturbs the particles in the surrounding medium, those particles disturb the particules next to them, and so on, as the sound propagates away from the vibration.
Acceleration is the rate of change of velocity per unit of time. Which of these is the formula for acceleration?
\(\vec{a} = \Delta \vec{v} t \) |
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\(\vec{a} = { t \over \Delta \vec{v} }\) |
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\(\vec{a} = { \vec{v} \over t }\) |
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\(\vec{a} = { \Delta \vec{v} \over t }\) |
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 \(\vec{a} = { \Delta \vec{v} \over t }\)
Materials like metals that transfer heat efficiently are called:
refractors |
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conductors |
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reflectors |
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insulators |
Heat is always transferred from warmer to cooler environments and conduction is the simplest way this transfer can occur. It is accomplished through direct contact between materials and materials like metals that transfer heat efficiently are called conductors while those that conduct heat poorly, such as plastic, are called insulators.
Examples of primary consumers include:
fish |
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cows |
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all of these |
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rats |
Primary consumers (herbivores) subsist on producers like plants and fungus. Examples are grasshoppers, cows, and plankton.
What kind of weather front is likely to create clouds and storms?
temperate front |
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cold front |
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warm front |
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stationary front |
A warm front is the boundary between warm and cool (or cold) air when the warm air is replacing the cold air. Warm air at the surface pushes above the cool air mass creating clouds and storms.