How to determine if the space ship is moving or stopped?

[songoku]

Homework Statement

Tom is in a spaceship without windows and can not know outside condition. How can he know if the ship is moving with constant speed or stops?
a. Measure the apparent speed of light in the spaceship
b. Measure your precision watch. If it runs slower, the spaceship is moving
c. Measure the length of an object. If it is shorter, the spaceship is moving
d. Impossible to determine

Homework Equations

Not sure

The Attempt at a Solution

Option (a) is wrong because speed of light is constant in all frame of reference

Option (b) and (c) are wrong because Tom can not compare his reading with external condition so he can not know whether his time measurement is slower or his length measurement is shorter.

So the answer is (d)?

Thanks

 

[Abhishek11235]

D is correct option. There is no way in which observer can determine whether he is moving or at rest. In SRT,the moving observer thinks that his measurements are true and unchanged. Everything is going smoothly. It is some other inertial frame whose measurements are quite different then the person on the ship measures.

 

[songoku]

Thank you very much

 

[alejandromeira]

D is the correct option.

Apart from the answers of the subject:
Any stops acceleration will be observed by Tom as a gravitational field, and so, as Tom doesn't known anything about the exterior of the space ship, he won't be able to know if the spaceship is slowing down, whatever he does.

 

[Ray Vickson]

Homework Statement

Tom is in a spaceship without windows and can not know outside condition. How can he know if the ship is moving with constant speed or stops?
a. Measure the apparent speed of light in the spaceship
b. Measure your precision watch. If it runs slower, the spaceship is moving
c. Measure the length of an object. If it is shorter, the spaceship is moving
d. Impossible to determine

Homework Equations

Not sure

The Attempt at a Solution

Option (a) is wrong because speed of light is constant in all frame of reference

Option (b) and (c) are wrong because Tom can not compare his reading with external condition so he can not know whether his time measurement is slower or his length measurement is shorter.

So the answer is (d)?

Thanks

The question itself is poorly thought-out: in relativity there is no meaning to words such as "moving" or "stopped" without some further context. Moving with respect to what? Stopped with respect to what? As far as we know currently, there is no universal "rest frame" against which other frames can be assessed. There is, however --- at least in the absence of gravitation --- a meaningful notion of "absolute un-acceleratedness".

 

[songoku]

Thank you very much for all the help