Physics 7 (Winter 08) – Homework #5

Due: 2/12

1.      Two astronauts in different spacecraft make a very large number of experiments and obtain identical results for each. What can be concluded about their motion?

2.      One characteristic difference between light and sound is that

    1. Light does not go around obstacles as sound does
    2. Light moves at constant speed
    3. Sound travels faster than light
    4. Sound does not need a medium to propagate
    5. Light does not need a medium to propagate

3.      One common property of waves and particles is that

    1. Both always travel at the same speed
    2. Both go around obstacles
    3. Neither goes around obstacles
    4. Both need a medium to propagate
    5. Neither travels at infinite speed

4.      The shorter the wavelength of a wave is

    1. The faster it travels
    2. The longer the distance between crests
    3. The longer the height between crests and troughs
    4. The slower it propagates
    5. The shorter the distance between troughs

5.      When John says Mary is traveling at 5 miles per hour

    1. Everyone will agree with this statement
    2. Only people at rest with respect to John will agree with this statement
    3. No one else will agree with this statement
    4. Only people not accelerating with respect to John will agree with this statement
    5. Only people at rest with respect to John and very close to him will agree with this statement

6.      The speed of a beam of light

    1. Is independent of the velocity of the source, but depends on the acceleration of the source
    2. Is independent of both the velocity and acceleration of the source
    3. Is independent of the acceleration of the source, but depends on the velocity of the source
    4. Depends on both the acceleration and velocity of the source
    5. Depends on the velocity of the source but only when that velocity is very close to the speed of light

7.      According to 19th century physics the ether was supposed to be

    1. An anesthetic
    2. An insulator of electric effects between particles
    3. The medium in which light propagates
    4. The medium in which sound propagates
    5. An insulator of magnetic effects between particles

8.      If the ether did exist then

    1. It would lie completely outside our atmosphere
    2. The motion of the Earth would have no effect on the propagation of light as seen form Earth
    3. The motion with respect to the ether would always increase the speed of light
    4. The motion with respect to the ether would always decrease the speed of light
    5. Your eyes would be filled with it and if someone extracted the ether from your eyes you would see nothing even tough you would not be blind.

9.      One difference between light and sound is that

    1. Sound carries no energy
    2. Only sound needs a medium to propagate
    3. Only light needs a medium to propagate
    4. Light moves slower
    5. Only sound is a wave

10.  Microwaves and gamma rays

    1. Travel at different speeds but have similar wavelengths
    2. Cannot travel in a vacuum
    3. Travel at the speed of  light, but have different wavelengths
    4. Travel only where there is ether
    5. Differ in that gamma rays cannot “go around obstacles” like other waves, but microwaves can.