AP Physics: Special Relativity flashcards

Question 1

What kind of reference frame is it in which an object with no net force on it stays at rest or moves in a straight line at constant speed?

Accepted Answer

An inertial frame of reference

Question 2

Which postulate of Einstein says the laws of physics hold in their simplest form in every inertial frame?

Accepted Answer

The first postulate of special relativity

Question 3

Which postulate of Einstein says the speed of light does not depend on the source?

Accepted Answer

The second postulate of special relativity

Question 4

What is the phenomenon called in which time passes more slowly for an observer who moves relative to another observer?

Accepted Answer

Time dilation

Question 5

What is the mass of an object called when measured by someone at rest relative to it?

Accepted Answer

Rest mass

Question 6

What is the energy of an object at rest, E0 = mc², called?

Accepted Answer

Rest energy

Question 7

What is the energy E = γmc² called?

Accepted Answer

Total energy

Question 8

What is the method called of adding velocities as ordinary numbers, u = v + u′, which works when speeds are far below c?

Accepted Answer

Classical velocity addition

Question 9

What is the method called of adding velocities given by u = (v + u′)/(1 + vu′/c²)?

Accepted Answer

Relativistic velocity addition

Question 10

What is the change in observed wavelength of radiation from a source moving relative to an observer, at relativistic speeds, called?

Accepted Answer

The relativistic Doppler effect

Question 11

What is the lengthening of the observed wavelength called when a source moves away from the observer?

Accepted Answer

Red shift

Question 12

What is the shortening of the observed wavelength called when a source moves toward the observer?

Accepted Answer

Blue shift

Question 13

What is the supposed paradox called in which a twin who travels away and back at relativistic speed ages less than the twin who stays on Earth?

Accepted Answer

The twin paradox

Question 14

How does the speed of light in a vacuum depend on the observer's motion relative to the source?

Accepted Answer

It does not; every observer measures the same speed c

Question 15

Which speed can an object with mass never reach?

Accepted Answer

The speed of light in a vacuum

Question 16

How does the speed of light in matter compare with its speed in a vacuum?

Accepted Answer

It is lower in matter

Question 17

What did the Michelson-Morley result imply light does not need in order to travel?

Accepted Answer

A medium to carry it

Question 18

Which property of two events, occurring at the same time for one observer, is not absolute for all observers?

Accepted Answer

Simultaneity

Question 19

Compared with the time other observers measure for an event, is the proper time shorter or longer?

Accepted Answer

Shorter

Question 20

Which quantity is classical momentum multiplied by γ?

Accepted Answer

Relativistic momentum

Question 21

What value does γ approach when speeds are much less than c?

Accepted Answer

1

Question 22

What happens to relativistic momentum as an object's speed approaches c?

Accepted Answer

It grows without limit

Question 23

What happens to the rest mass of an object when energy is stored in it?

Accepted Answer

It increases

AP Physics: Special Relativity flashcards

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