Chapter 9 Review - Physics for Queensland U3&4

A spaceship moves towards you at a speed of 1/3c, where c is the speed of light. The spaceship emits a beam of light in your direction. As measured in your frame of reference, the speed of the light emitted by the spaceship is:

• 4/3 c

• c

• 2/3 c

• 1/3 c

Select the statement that describes one of the key postulates of Einstein's theory of special relativity.

• Nothing can travel faster than the speed of light.

• The laws of physics are the same in all inertial (non-accelerated) frames of reference.

• All inertial observers obtain the same result when measuring the time and position of an event.

• Time dilates for a moving observer.

Select the option about which observers in different inertial systems will agree.

• The simultaneity of events at separate locations

• The rate at which their clocks run

• The number of seconds elapsed for an event

• None of the above

The theory of special relativity treats problems involving:

• an inertial frame of reference

• a non-inertial frame of reference

• a fast-moving frame of reference

• an accelerated frame of reference.

The muon detection experiment helped confirm one aspect of special relativity, namely that:

• to a muon, distance was contracted

• muons are created in the upper atmosphere

• muons are relatively short-lived

• fewer muons reach the ground than expected.

If you approach a lamp while travelling at seven-tenths the speed of light (0.7c), you will measure the speed of light from the lamp to be:

• 0.49c

• 0.70c

• 1.0c

• 1.7c

A train is travelling at 0.9c along a straight, horizontal track at a constant speed approaches a rail crossing that flashes a light once per second. An observer on the train will measure the time between flashes to be:

• somewhat greater than one second

• equal to one second

• somewhat less than one second

• much greater than one second.

Proper time interval is the elapsed time between two events measured in a frame of reference in which the two events:

• are simultaneous

• occur at the same time

• are measured with synchronised clocks

• occur at the same point in space.

A meteor is heading for a planet at high speed. Select the statement that best describes the time of a meteor’s descent to the planet’s surface as measured aboard the meteor, and the time as measured by the observers on the surface of the planet.

• Only observers on the meteor measure the proper time.

• Both measure proper time in their own reference frames

• Neither measure proper time.

• Only the observers on the planet measure proper time.

Select one of the following natural phenomena that cannot be explained by Newtonian physics.

• the absence of muons anywhere in the atmosphere

• the presence of muons in the atmosphere

• the relatively high number of muons close to Earth

• the relatively low number of muons close to Earth Short answer