Gravity and Space Exploration

1. When at rest on the launching pad, the force of gravity on the space shuttle is quite huge—the weight of the shuttle. When in orbit, some 200 km above Earth’s surface, the force of gravity on the shuttle is 1. nearly as much.2. about half as much.3. nearly zero (micro-gravity).4. zero. (Neglect changes in the weight of the fuel carried by the shuttle.)

2. 1. nearly as much.2. about half as much.3. nearly zero (micro-gravity).4. zero. When at rest on the launching pad, the force of gravity on the space shuttle is quite huge—the weight of the shuttle. When in orbit, some 200 km above Earth’s surface, the force of gravity on the shuttle is (Neglect changes in the weight of the fuel carried by the shuttle.)

3. Consider a giant flat plate that touches the Earth at one point and extends out into space. Suppose you slide an iron block along the plane, where it makes contact with the Earth.Suppose also that the plate is perfectly frictionless, air drag is absent, and vo < vescape. The block will 1. continue at constant velocity, in accord with the law of inertia.2. increase in speed as the force of gravity on it weakens with distance.3. decrease in speed due to the pull of gravity.4. oscillate to and fro.

4. 1. continue at constant velocity, in accord with the law of inertia.2. increase in speed as the force of gravity on it weakens with distance.3. decrease in speed due to the pull of gravity.4. oscillate to and fro. Consider a giant flat plate that touches the Earth at one point and extends out into space. Suppose you slide an iron block along the plane, where it makes contact with the Earth.Suppose also that the plate is perfectly frictionless, air drag is absent, and vo < vescape. The block will

5. If the Sun suddenly collapsed to become a black hole, the Earth would 1. leave the Solar System in a straight-line path.2. spiral into the black hole.3. continue to circle in its usual orbit.

6. 1. leave the Solar System in a straight-line path.2. spiral into the black hole.3. continue to circle in its usual orbit. If the Sun suddenly collapsed to become a black hole, the Earth would

7. Suppose the gravitational force between the Earth and Moon was turned off and the pull replaced by the tension in a steel cable joining them. Consider the tension in such a cable, and its size. The tensile strength of a steel cable is about 5.0  108 N/m (each square meter cross section can support a 5.0  108–Newton force). The cross-sectional area would be about that of1. a bass guitar string.2. a typical vertical cable that supports the Golden Gate Bridge.3. the Empire State building.4. Manhattan Island, N.Y.5. an area greater than New York State.

8. The cross-sectional area would be about that of1. a bass guitar string.2. a typical vertical cable that supports the Golden Gate Bridge.3. the Empire State building.4. Manhattan Island, N.Y.5. an area greater than New York State. Suppose the gravitational force between the Earth and Moon was turned off and the pull replaced by the tension in a steel cable joining them. Consider the tension in such a cable, and its size. The tensile strength of a steel cable is about 5.0  108 N/m (each square meter cross section can support a 5.0  108–Newton force).

9. Ocean tides are produced by the Moon. Since our bodies aremostly water, doesn’t the Moon similarly produce tides in our bodies? 1. Yes, there are biological tides that affect mood and behavior.2. Yes, but negligible (less than are produced by an apple you hold over your head).3. No, because the water in our body isn’t free to flow.

10. 1. Yes, there are biological tides that affect mood and behavior.2. Yes, but negligible (less than are produced by an apple you hold over your head).3. No, because the water in our body isn’t free to flow. Ocean tides are produced by the Moon. Since our bodies aremostly water, doesn’t the Moon similarly produce tides in our bodies?

11. Would observers on the Moon see the Earth “rise” and “set,” as we here on Earth see the Moon rise and set? 1. Yes2. No

12. 1. Yes2. No Would observers on the Moon see the Earth “rise” and “set,” as we here on Earth see the Moon rise and set?