Unformatted text preview: 1 Chapter 4 Post‐lecture Quiz 1. What are possible units for velocity? 1. Feet / sec 2. Meters / sec 3. Inches / year 4. Meters / sec / sec 5. 1, 2, or 3 2. What’s the difference between velocity and speed? 1. They have different units 2. Velocity includes speed and direction 3. None, they are different words for the same thing 3. Which of the following is true? 1. You can have acceleration not equal zero, but velocity equal to zero 2. You can have acceleration equal to zero, but velocity not equal to zero 3. You can accelerate without changing your speed 4. 1 and 2 5. 1, 2, and 3 4. Momentum = 1. Mass x velocity 2. Mass x acceleration 3. Rate of change of position 4. Any of the above 5. 1 and 3 5. Changing an object’s angular momentum requires 1. Gravity 2. Applying a force 3. Applying a torque 4. Friction 5. None of the above 6. Newton’s second law, F = m∙a, (force = mass x acceleration), means that with no force, 1. Objects remain at rest 2. An object’s speed doesn’t change 3. An object’s velocity doesn’t change 4. 2 and 3 7. If a planet travels in a circular orbit without speeding up or slowing down, does it have a force on it? 1. No 2. Yes 2 8. Does Newton’s second law, F = m∙a, apply to: 1. A planet orbiting a star other than the Sun? 2. Two binary stars orbiting each other? 3. The force needed to swing a rock on a string? 4. The force needed to push a car or bicycle? 5. All of the above? 9. Newton’s third law says that for every force there is an equal and opposite reaction force. For rockets, this means: 1. If a rocket shoots gas out the back, the rocket moves forward 2. #1 is only true if there is air to push against. It is not always true 10. Newton’s law of gravity is F = G m1 m2 / d2 Can this be used to find the force between the Earth and YOU? If so, what is d? 1. No 2. Yes, d is the diameter of the Earth 3. Yes, d is the distance from you to the ground 4. Yes, d is the distance from you to the center of the Earth 11. What is the common name for the force of gravity between the Earth and you? 1. Terrestrial gravity 2. Your gravity force 3. Your weight 4. Your mass 12. Which of the basic types of energy is illustrated when you stand on a ladder? 1. kinetic 2. potential 3. radiative 4. heat 5. None of the above 13. Which is an example of changing gravitational potential energy into kinetic (motion) energy? 1. Eating food and releasing the energy 2. Riding a bicycle 3. Falling off a ladder 4. A gas cloud in space contracting due to gravity and heating up 5. 3 and 4 14. Temperature is a measure of: 1. How much heat an object contains 2. How fast atoms are moving 3. How hot you feel when you touch something 4. Energy 3 15. The total kinetic energy something contains is called its: 1. Heat, heat content, or thermal energy 2. Temperature 3. Mean energy 4. None of the above 16. A cake is baking at 400 degrees. If you briefly touch the cake you will not be burned. If you touch the metal pan for the same length of time you will be burned. Why? 1. The metal is hotter than the cake 2. The metal is denser than the cake–there are more atoms per unit volume 3. The metal is a better conductor 4. 2 and 3 5. All of the above 17. What causes the tides? 1. Gravity 2. Gravity from the Moon pulling on water 3. Gravity from the Moon is stronger on one side of the earth than the other 4. Gravity from the Moon or the Sun is stronger on one side of the earth than the other 18. When I drive my car at 30 miles per hour, it has more kinetic energy than it does at 10 miles per hour. 1. Yes, it has three times as much kinetic energy. 2. Yes, it has nine times as much kinetic energy. 3. No, it has the same kinetic energy. 4. No, it has three times less kinetic energy. 5. No, it has nine times less kinetic energy. 19. Unique experiments can be carried out in the Space Station because of the lack of gravity. 1. Yes, and the Space Station was built in order to escape gravity. 2. This is not quite right ‐ the Space Station still feels the effect of the Earth’s gravity but it is greatly diminished and the experiments are therefore referred to as being performed in “micro‐ gravity.” 3. No, the uniqueness of the experiments is not due to the lack of gravity but to weightlessness. 4. No, similar experiments can be performed on the surface of the Earth. 5. No, similar experiments can be performed on the highest mountaintops on Earth. 20. If you could go shopping on the Moon to buy a pound (weight) of chocolate, you’d get a lot more chocolate than if you bought a pound on Earth. 1. Yes, because of the lower gravity on the Moon, it would take more chocolate to weigh a pound than on Earth. 2. Yes, chocolate would have a lower density on the Moon and therefore more is needed to reach a pound in weight. 3. No, a pound on the Moon is the same as a pound on Earth. 4. No, chocolate weighs the same on the Moon as on Earth. 5. No, mass (and energy) are always conserved. ...
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 Spring '08
 OESCH
 Gravity, space station, 10 miles, 30 miles, 400 degrees

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