What is the Great Wall?
A) It is a ridge on the Moon near the crater Birt.
B) It is the distance beyond which astronomers cannot view any more galaxies or even quasars.
C) It is a large sheet of galaxies.
D) It is the time before the universe started expanding, about which we can never know anything.
E) It is an enormous intergalactic cloud of dust and gas that hides more distant galaxies.
Question 2
Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight?
A) The ball's gravitational potential energy is greatest at the instant it returns to hit the ground.
B) The ball's gravitational potential energy is greatest at the instant when the ball is at its highest point.
C) The ball's gravitational potential energy is always the same.
D) The ball's gravitational potential energy is greatest at the instant the ball leaves your foot.