What does the word "normal" mean in the phrase "normal force"?
A) the force that is usually exerted by a surface
B) the total force exerted by a surface
C) the component of the force exerted by a surface parallel to the surface
D) the component of the force exerted by a surface perpendicular to the surface
E) the force is due to contact between two objects.
D
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What is in the box shown below? 
A. Positive charge B. Negative charge C. Zero charge D. One cannot determine the charge’s sign from this diagram.
How do astronomers think Jupiter generates internal heat?
a. fusion b. chemical reactions c. friction due to its fast rotation d. shrinking and releasing gravitational potential energy e. tidal heating
Which of the following statements regarding the H-R diagrams of star clusters is NOT correct?
A. A very young cluster will have stars that lie in the right-hand side and a little above the main sequence. B. A very young cluster will not show a turn-off point. C. A very old cluster will have many stars in the upper left corner of the H-R diagram. D. A very old cluster will show a turn-off point and will have many red and yellow giant stars. E. A very young cluster will not have all its stars on the main sequence.
Which stars are more common?
A) black holes B) white dwarfs C) White dwarfs and neutron stars are about equally common. D) Neutron stars and black holes are about equally common. E) neutron stars