In: Physics
What is true when it comes to the concept of FLOATING FREE in SPECIAL RELATIVITY, choose one of the three alternatives each for a) - d)
a) AN OBSEVER NEEDS ACCESS TO (1. His own watch (wrist-watch time) - 2. All synchronised watches in ALL Free-Float Frames - 3. All synchronised watches in ONE Free-Float Frame)
b) A TEST-PARTICLE (1. Has zero mass - 2. Generates neglectable gravitational field - 3. Is a standardised particle (SI-standard)
c) FREE-FLOAT FRAME IS USED BECAUSE (1. It makes gravity stronger - 2. It makes gravity weaker - 3. It makes gravity ”disappear”)
d) A FREE-FLOAT FRAME NEEDS TO BE LOCAL BECAUSE (1. Gravitational field can be different in different places - 2. To prevent zero effect on tide (high/low water) 3. To prevent the test particles mass to become zero)
Solution:
a)An observe needs access to 1. His own Watch (He can't rely on other synchronished watches because they may be on different float frames. The velocity of light is same in each frame of reference making the overall space-time constant. However, otherwise, space and time can be different in two different frames as can be seen by length contraction and time dilation.)
b)A test particle 1. Has no mass. (In metric theories of gravitation, particularly general relativity, a test particle is an idealized model of a small object whose mass is so small that it does not appreciably disturb the ambient gravitational field. This mass is considered to be zero (approx))
c)A FREE-FLOAT FRAME NEEDS TO BE LOCAL BECAUSE 1. Gravitational field can be different in different places (The relativity postulate : the laws of physics apply in every inertial reference frame. The speed of light postulate : The speed of light in vacuum is the same for any inertial reference frame (c = 3.00 x 108 m/s). This is true no matter how fast a light source is moving relative to an observer.)