Q1. A planet has two moons of equal mass. Moon 1 is in a circular orbit of radius r. Moon 2 is in a circular orbit of radius 2r. What is the magnitude of the gravitational force exerted by the planet on Moon 2?
a. Four times as large as that on Moon 1
b. Twice as large as that on Moon 1
c. Equal to that on Moon 1
d. Half as large as that on Moon 1
e. One-fourth as large as that on Moon 1
Q2. Superman stands on top of a very tall mountain and throws a baseball horizontally with a speed such that the baseball goes into a circular orbit around the earth. While the baseball is in the orbit, what is the magnitude of the acceleration of the ball?
a. It depends on how fast the baseball is thrown
b. It is zero because the ball does not fall to the ground
c. It is slightly less than 9.80 m/s^2
d. It is equal to 9.80 m/s^2
Q3. A comet moves in an elliptical orbit around the sun. Which point in its orbit (perihelion or aphelion) represents the highest value of:
a. The speed of the comet
b. The potential energy of the comet-sun system
c. The kinetic energy of the comet
d. The total energy of the comet-sun system?