Will see the same speed for the ball always?

  • Thread starter Hepic
  • Start date
  • #1
118
0

Main Question or Discussion Point

We have two people. A person(A) that is stadning and another(B) one who drives his car,so he has some velocitty. Lets say that the person B throw a photon from his car. Lets suppose that photon will hit down and will go up again. So both guys see the same speed.
But If instead of light,he throw a ball then both will see the same speed for the ball always?
 

Answers and Replies

  • #2
PAllen
Science Advisor
2019 Award
7,978
1,265
No, there is a unique invariant speed, which we call the speed of light. According to relativity, there is one formula that covers all cases such as you describe:

Suppose B is moving at v relative to A. Suppose A throws 'something' at velocity u as measured by A. Then B sees the 'something' moving at:

(u-v)/ (1 - uv/c^2)

If you put u=c, you get c also for what B sees. For any other value of u, you get a different speed as observed by B. for u much less than c, this formula becomes empirically indistinguishable from u-v. But it is one formula for all cases.
 

Related Threads on Will see the same speed for the ball always?

  • Last Post
2
Replies
32
Views
10K
Replies
3
Views
827
Replies
3
Views
803
Replies
21
Views
3K
Replies
42
Views
6K
Replies
6
Views
2K
Replies
14
Views
2K
Top