Special Relativity: Time Dilation (1 Viewer)

[AMorris]

A spaceship flies past a planet at .6c. The pilot and his girlfriend on the planet each wave at each other for 4.0 seconds.
(a) Calculate how long the pilot sees his girlfriend waving.
(b) Calculate how long the girlfriend sees the pilot waving.

This is from Dot-Point and the answers they give are (a) 3.2 seconds, (b) 5.0 seconds. But those answers seem wrong to me as the situations seem symmetric in regards to special relativity and thus I'd assume both would see the moving clock as running slow compared to their clocks, so I would have thought the answer to both questions was 5.0seconds. However I have found Dot-Point to be quite reliable so I may be wrong. Any ideas?

 

[sanjeevprasad99]

ummmm i agree with u.....i seem to get 5s as well.....im pretty shure the book is wrong....i hav found some mistakes in that book
tho....someone might prove 3.2s....

 

[sanjeevprasad99]

WAIT, IM WRONG!!! IT IS 3.2!!!!!!!!! IM FKN STOOPID!!!!!
ok here
u hav to rearange the formula
i.e
tv = to/........

to

to = tv times square root 1 -....
thats how u do it

 

[SoulSearcher]

WAIT, IM WRONG!!! IT IS 3.2!!!!!!!!! IM FKN STOOPID!!!!!
ok here
u hav to rearange the formula
i.e
tv = to/........

to

to = tv times square root 1 -....
thats how u do it

But why would you do that?

No inertial frame of reference should be preferred in this situation. The pilot waving to his girlfriend for 4.0 seconds is symmetric to the girlfriend waving to the pilot for 4.0 seconds. Both the pilot and the girlfriend should see time dilated in the other person's frame of reference, hence to each person, the other person would be waving for 5.0 seconds each. I don't have a really good understanding of this particular bit of the syllabus, but it seems to me that both the pilot and the girlfriend would see each other wave for 5.0 seconds each. I would check up on that though Morris

 

[polyspaston]

It is true that no two inertial frames of reference be preferred over the other. This is the reason why we have the twins paradox effect. As a result, the girlfriend would see the pilot moving away at 0.6c, and the pilot would see the girlfriend move away at 0.6c. This means that in both frames of reference, time has been dilated so they both observe each other waving for 5s. Now, this answer is based on the assumption that the earth was the only frame of reference from which the pilot made his observation. Therefore, the answer for (a) and (b) should both be 5s.

 

[sanjeevprasad99]

i asked my phys teacher...n he said they both should b 5 as well, o well

 

[Forbidden.]

The Twin Paradox should clarify this.