1. A big 18-wheel truck collides head-on with a fly on I-25. The 18-wheeler was going at 70 miles/hr to the north, the fly at 2ft/sec to the south. Which of the following describes the situation best?

a. The fly barely survived the collision.

b. The fly exerted a larger force on the 18-wheeler than the 18-wheeler on the fly.

c. The 18-wheeler exerted a larger force on the fly than the fly on the 18-wheeler.

d. The forces exerted by the two bodies on each other were equal.

2. Would you rather be the fly or the 18-wheeler? Why?

3. If the Earth were half the size that it has, without changing its mass, how different would our weight be on the surface? (The weight equals the force of gravity on you).

a. Factor 2 smaller.

b. Factor 2 larger.

c. Factor 4 smaller.

d. Factor 4 larger.

e. The same, since our weight doesn't change.

4. A planet has 8 times the mass of Earth and twice its radius. What would your weight be on the surface of that planet?

a. Same as on Earth.

b. Eight times larger than on Earth.

c. Twice as large as on Earth.

d. Four times smaller than on Earth.

5 (i). According to Newton's action=reaction law, if you jump up, the Earth moves a bit away from you.

a. True

b. False

(ii). What happens on your way down with the Earth, if anything?

6. Astronauts on board the space station are "weightless". This means that there is no force of gravity acting on them.

a. True

b. false

7. Which of the following individuals would be in a "weightless situation"?

a. As astronaut walking on the moon.

b. An astronaut in the space shuttle when it is launched.

c. An astronaut in space craft (that is not firing its rockets at the time) on its way to Mars.

d. Captain Kirk in starship enterprise.

8. Suppose I stand on a scale while going up an elevator. At the top the elevator stops. Before I can get out, the cables break and entire elevator falls down. Just before the crash, I still manage to read my weight on the scale. What would it say?

a. my usual weight.

b. a higher than usual weight.

c. a lower than usual weight.

d. 0 lbs.

9. A rocket engine pushes the rocket forward because the exhaust gasses from the rocket push against the surrounding air.

A. True B. False