Physics 7 homework #3

        Due 4/21/09

  1. Imagine a transparent airplane flying steadily at 800 mph (no change in direction, speed or altitude). Inside the plane a passenger drops a book, and this incident is observed also by an observer on the ground. Then
    1. Both the passenger and the ground observer see the book fall straight down
    2. The passenger sees it move towards the back of the plane as it falls while the ground observer sees it fall straight down
    3. Both passenger and ground observe r see the book fall down and back towards the tail of the plane
    4. The passenger sees the book fall straight down, the ground observer sees it fall down and towards the front of the plane
  2. Two discoveries of Galileo that pitted him against the prevalent notions of his time were
    1. His observation of Jupiter’s satellites and his support of the heliocentric hypothesis
    2. His observation that the sun moves across the sky and that the Earth is round
    3. His claim that the Earth is flat and that the universe is eternal
    4. His belief that all is made only of water and that space was finite
  3. What is an inertial observer?
    1. One that is hard to move
    2. One that finds that  free bodies move at constant speed in a straight line
    3. One that it steadily accelerating
    4. One that is at rest with respect to the Earth
  4. What would happen to the Moon if the Earth's force of gravity suddenly disappeared (ignoring the effects of other celestial bodies)?
    1. The Moon would move away from the Earth traveling at constant speed in a straight line
    2. The Moon would fall toward the Earth
    3. They would both fall towards the Sun
    4. Nothing, the Moon would continue to circle the Earth because of the centrifugal force.
  5. Two bodies a released form a given height (on Earth), as they fall
    1. Their velocities and accelerations are the same
    2. Their velocities are the same, but their accelerations are different
    3. Their velocities are different, but their accelerations are the same
    4. their velocities and accelerations are different
    5. Because the Moon has a fiery component and so it cannot, by its own nature, fall towards Earth
  6. You are driving at a constant speed of 65 mph on a straight freeway, what is your velocity and acceleration with respect to the road:
    1. Velocity = 0                Acceleration = 0
    2. Velocity = 0                Acceleration = 65 mph
    3. Velocity = 65 mph      Acceleration = 0
    4. Velocity = 65 mph      Acceleration = 65 mph
  7. According to Galileo, would a Martian astronomer looking at the Earth find that
    1. Neither Earth nor Venus will exhibit phases
    2. Only Earth will exhibit phases
    3. Both our planet and Venus will exhibit phases
    4. Only Venus will exhibit phases
  8. If a ball is set in motion on a horizontal table it eventually stops, why?
    1. Because the ball’s natural motion is downwards not horizontal
    2. Because there is no force making it move
    3. Because gravity pulls it to a stop
    4. Because of friction
  9. Two spaceships, L and R, pass each other, the astronaut in L claims that R moves to the right at 1,000 km/s, while R claims that L moves left at 1,000 km/s. Who is right?
    1. L is right
    2. R is right
    3. They are both right
    4. Neither is right
  10. “Absolute space and time” means
    1. That they depend on the observer
    2. That they depend on the observer, but only if he/she is in an inertial reference frame
    3. That they are unaffected by any objects
    4. That they depend on the observer, but only if he/she is in an non-inertial reference frame