The sky is dark at night:
A) because the stars in the Milky Way are far away.
B) because the Sun is on the other side of Earth.
C) because there are far fewer stars on the night side of Earth.
D) because all the light from all the objects in the universe hasn't arrived here yet.
E) because the quasars are too far away from Earth for their light to have arrived here.
D
You might also like to view...
Suppose two charges, one positive and one negative, are separated by a distance d. Where can two equipotential surfaces at different potentials intersect in the region near the charges?
a. halfway between the charges if the charges have the same magnitude b. closer to the smaller negative charge than the larger positive charge if the charges are not equal c. Equipotential surfaces at different potentials cannot intersect. d. closer to the smaller positive charge than the larger negative charge if the charges are not equal
A proton moving at 3 × 10^4 m/s is projected at an angle of 30° above a horizontal plane. If an electric field of 400 N/C is directed downwards, how long does it take the proton to return to the horizontal plane? (HINT: Ignore gravity.) [mProton = 1.67 × 10^?27 kg, qProton = +1.6 × 10^?19 C.]
Galaxy A is 300 Mpc from Galaxy B. Hubble's Law says that V=H0 x D. About how fast is Galaxy A receding from the perspective of Galaxy B? Use a value of 75 km/s/Mpc for Hubble's constant.
A. 225 km/s B. 30000 km/s C. 75 km/s D. 22500 km/s E. 15000 km/s
Kaitlin uses a bat to hit a thrown baseball. She knocks the ball back in the direction from which it came in a partially inelastic collision. The bat, which is heavier than the baseball, continues to move in the same direction after the hit as Kaitlin "follows through." Is the ball moving faster before or after it was hit?
a. The ball was moving faster before it was hit. b. The ball was moving faster after it was hit. c. The ball was moving at essentially the same speed before and after the hit. d. There is insufficient information to answer this problem.