Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)
A) The red star is more massive than the blue star.
B) The blue star is more massive than the red star.
C) The red star is farther away than the blue star.
D) The blue star has a hotter surface temperature than the red star.
E) The red star has a hotter surface temperature than the blue star.
D) The blue star has a hotter surface temperature than the red star.
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When heat is added to boiling water, its temperature
A) increases. B) decreases. C) remains unchanged. D) none of the above
According to Kepler's second law, Halley's Comet circles the Sun in an elliptical path with the Sun at one focus of the ellipse. What is at the other focus of the ellipse?
a. nothing b. the Earth c. The comet itself passes through the other focus. d. The tail of the comet stays at the other ellipse.
An object weighs 7.84 N when it is in air and 6.86 N when it is immersed in water of density 1000 kg/m3. What is the density of the object?
A) 6000 kg/m3 B) 7000 kg/m3 C) 8000 kg/m3 D) 9000 kg/m3
If you shout across a canyon and the echo returns in four seconds, how far away is the other side? (Velocity of sound in air is 300 m/s)
a. 150 b. 300 c. 600 d. 1200 e. 2400 meters