U1.5 Special relativity

Question 1

What is the speed of light in a vacuum?

Answer 1

3.0 x10*8

Question 2

An observer on earth notes the speed of light to be 1.0c . What will an observer on the moon note it to be?

Answer 2

1.0c . The speed of light in a vacuum is the same for all observers

Question 3

What is a frame of reference?

Answer 3

A coordinate system inside which the motion of an object can be described. Laws of motion hold true in any frame of reference with constant velocity (inertial frames of reference)

Question 4

What are Einstein’s two postulates?

Answer 4

1) The speed of light is constant to all observers regardless of their velocity (proved experimentally).
2) The law’s of physics are the same for all freely moving observers.

Question 5

What is time dialation?

Answer 5

The difference in the elapsed time as measured by two clocks. Time doesn’t pass at a fixed rate. The length of time depends on the difference between frames of reference.

Question 6

Does time pass faster or slower for object moving fast?

Answer 6

Slower

Question 7

What is length contraction?

Answer 7

The phenomenon that a moving object’s length is measured to be shorter than its proper length, which is the length as measured in the object’s own rest frame

Question 8

Do faster moving objects appear longer or shorter?

Answer 8

Shorter

Question 9

Do faster moving objects appear longer or shorter?

Answer 9

Shorter

Question 10

Why can the effects of special relativity be disregarded for an object moving 0.05c (5% the speed of light)?

Answer 10

Because the effects are not noticed unless an object is travelling at more than about 0.1c (10% the speed of light).

Question 11

What happens when you approach the speed of light?

Answer 11

• Time is observed to slow down until it would take infinitely long for a single tick.
• Length is observed to contract to zero.