Gravity assist: The incoming and outgoing velocities of the probe relative to the planet is the same, but some of the angular momentum from the planet is transferred to the probe passing, thus increasing its velocity relative to the sun. The change in momentum does not affect the planet much due to its large mass, but this provides significant velocity increase for the probe (when you got the probe flying right, of course, so that the magnitude of the resultant velocity vector of the probe is larger than the velocity vector of the probe before the encounter).
Postulates: 1. All laws of phys (including mechanics and electromagnetism) apply in the same way in all inertial frames of reference. 2. constant c.
Definition of metre changed to base on a constant quantity, c, instead of some arbitrary value such as a fraction of the distance between the pole and the equator along the meridan through Paris or something, which can also change over time.
Events that are simultaneous in one frame of reference are not necessarily so in other frames in relative constant motion. Take that thought experiment, for example, with the light bulb in the middle of a train moving at constant velocity with two light-controlled gates at each end. To a person in the middle of the train, the distances the light beam has to travel to both doors are the same, thus the doors open simultaneously; to a person on the ground, however, light has more distance to travel to the front door than to the back door (since the train is moving forward), so the doors do not open simultaneously. This directly results from the constancy of light speed; and since there is no preferred frame of reference, both observations are valid, hence the concept of simultaneity is relative.
Concept of rest mass is required since mass dilation occurs ie. mass changes as velocity changes.
You should be able to find all this in textbooks. Which one do you use? I think the Jarcaranda one does the job quite well o.0
Light speed is the limiting speed, as you can see from mass dilation, mass of an object increases as its velocity increases, in turn requring more energy input for a same amount of acceleration, so the object never reaches speed of light. As rt(1-v
2/c
2) is less than one, from the formula for mass dilation, you can see that mass does increase as v approaches c. I'm looking for the thought experiment/s that demonstrate mass dilation too, but apparently you don't need to know how that comes about...They seem to only require you to be able to apply the formula, instead of knowing its derivation o.0 But we can always look it up
