- #1
BomboshMan
- 19
- 0
Need help understanding inertial frames of reference!
I'm doing an A2 physics unit on special relativity (AQA) and am really confused about this, but I only want to get the idea so don't go to deep please :)
I understand that a frame of reference is an area which is fixed relative to something (e.g. Our frame of reference is fixed relative to us). In my textbook it says that an inertial frames are frames of reference that are moving at a constant velocity relative to each other (not accelerating). My teacher (who's crap so I don't trust what he says) says that if there are two frames moving at constant velocity relative to each other, each of those frames are inertial frames themselves, but the whole thing overall (including both frames) is not inertial. So is the whole thing- including both frames- an inertial frame, or is each individual frame an inertial frame?
My revision book says that an inertial frame is one which Newton's first law applies...is this a definition, or just a way to test if something is an inertial frame? Also it gives an example of an accelerating train with a ball in it, the ball will move relative to the train without a force being applied, so Newton's first law is broken therefore it is a non-inertial frame...but is the train accelerating relative to something (another frame, e.g. the platform)? If so, how come the accelerating train is not just an inertial frame from the frame of reference of an observer on the platform?
One more thing (sorryyy)...one of Einsteins postulates is 'The laws of physics have the same form in all inertial frames'. What does that actually mean?
I hope I've explained what I mean okay...thanks :)
I'm doing an A2 physics unit on special relativity (AQA) and am really confused about this, but I only want to get the idea so don't go to deep please :)
I understand that a frame of reference is an area which is fixed relative to something (e.g. Our frame of reference is fixed relative to us). In my textbook it says that an inertial frames are frames of reference that are moving at a constant velocity relative to each other (not accelerating). My teacher (who's crap so I don't trust what he says) says that if there are two frames moving at constant velocity relative to each other, each of those frames are inertial frames themselves, but the whole thing overall (including both frames) is not inertial. So is the whole thing- including both frames- an inertial frame, or is each individual frame an inertial frame?
My revision book says that an inertial frame is one which Newton's first law applies...is this a definition, or just a way to test if something is an inertial frame? Also it gives an example of an accelerating train with a ball in it, the ball will move relative to the train without a force being applied, so Newton's first law is broken therefore it is a non-inertial frame...but is the train accelerating relative to something (another frame, e.g. the platform)? If so, how come the accelerating train is not just an inertial frame from the frame of reference of an observer on the platform?
One more thing (sorryyy)...one of Einsteins postulates is 'The laws of physics have the same form in all inertial frames'. What does that actually mean?
I hope I've explained what I mean okay...thanks :)