The _____ of a star is the time it takes the star to complete a cycle from bright to faint to bright again
A) life span
B) luminosity period
C) period of pulsation
D) half-life
C
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A beam of X-rays of different frequencies is reflected at 10 degrees off a crystal of interatomic spacing 0.2 nm. Which X-ray wavelength is preferentially reflected?
a. 0.0943 nm b. 0.139 nm c. 0.069 5 nm d. 1.02 × 10^-10 m e. 3.47 × 10^-11 m
You observe a full moon rising at sunset. What will you see 6 hours later?
A) a full moon on or near your meridian B) waning gibbous moon C) first-quarter moon D) a third-quarter moon
Earth exerts a gravitational force of 432 N on an object on its surface. Earth has radius R. If the object is raised to a height of 3R above Earth's surface, what is the gravitational force that Earth will exert on it?
A) 108 N B) 48.0 N C) 27.0 N D) 305 N E) 144 N
Suppose it takes 6 seconds for a watermelon to fall to the ground after being dropped from a tall building
If there were no air resistance, so that the watermelon would fall with the acceleration of gravity, about how fast would it be going when it hit the ground?