What makes stars twinkle?

a. Variations of light output from the distant stars.
b. Reflection by moving water.
c. Being close enough to Earth to appear as tiny discs rather than points of light.
d. The air near the surface of the earth is warmer than the air at the top of the atmosphere.
e. Constant tiny changes in refraction as air molecules move.


e

Physics & Space Science

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When the dew point is below 0°C, which of the following is likely to form?

a. Sleet b. Snow c. Hail d. Dew

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As a spaceship is moving toward Earth, an Earthling measures its length to be 325 m,

while the captain on board radios that her spaceship's length is 1150 m. (c = 3.00 × 108 m/s) (a) How fast is the rocket moving relative to Earth? (b) What is the TOTAL energy of a 75.0-kg crewman as measured by (i) the captain in the rocket and (ii) the Earthling?

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An object at the center of curvature of a concave mirror forms an inverted image at the center of curvature itself

Indicate whether the statement is true or false

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When a 20-V emf is placed across two resistors in series, a current of 2.0 A is present in each of the resistors. When the same emf is placed across the same two resistors in parallel, the current through the emf is 10 A. What is the magnitude of the greater of the two resistances?

a. 7.2 W b. 7.6 W c. 6.9 W d. 8.0 W e. 2.8 W

Physics & Space Science