What two things do we need to measure in order to determine a star's luminosity?
A) apparent brightness and distance
B) distance and mass
C) apparent brightness and temperature
D) apparent brightness and mass
A) apparent brightness and distance
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A 0.0030-kg lead bullet is traveling at a speed of 300 m/s when it embeds in a block of ice at 0°C. If all the heat generated goes into melting ice, what quantity of ice is melted? (Lf = 80 kcal/kg, the specific heat of lead = 0.03 kcal/kg•°C, and 1 kcal = 4186 J)
a. 1.47 × 10^-2 kg c. 3.2 × 10^-3 kg b. 4.0 × 10^-4 kg d. 2.6 × 10^-4 kg
The composition of Mercury's crust is:
A) deficient in volatile compounds that contain elements such as sulfur and potassium. B) consistent with material from the solar wind, indicating that Mercury has collected material over the last few billion years. C) similar to the crust of the other terrestrial planets. D) nearly identical to Mercury's mantle material.
A particle moves east at constant velocity v r for a time interval ?T. It then moves north at a constant velocity, with the same speed as before, for another time interval ?T. Finally it moves east again with the original velocity. At the instant an additional time interval ?T has elapsed, which of the following are true about the average velocity and the average acceleration for the motion described?
a. The average velocity is v r and the average acceleration is zero. b. The average velocity is v r and the average acceleration is not zero. c. The average velocity is not v r and the average acceleration is zero. d. The average velocity is not v r and the average acceleration is not zero.
Tycho's universe was the same as the Copernican universe except that
a. Earth did not move. b. the sun did not move. c. the moon orbited the sun. d. the orbits were elliptical with the sun at one focus. e. the orbits followed uniform circular motion.