# IB Physics Relativity

/A tutorial sheet of **true-false** questions on relativity is given below.

- The speed of light (according to the local observer) near a black hole is 3.0x10
^{8}m/s. A distant observer considers the speed of light to be much less than this. - The speed of light changes (according to a distant observer) as it passes through a gravitational field.
- The speed of light is the same for all observers in a flat space.
- Space can expand at a rate greater than c.
- Nothing can escape from inside a black hole.
- Particles can escape from the event horizon of a black hole.
- Light leaving the horizon of a black hole undergoes a gravitational red shift and has an infinite wavelength at infinity and so cannot be detected.
- The time coordinate of an event is the same value at all locations in the same inertial reference frame.
- If an event occurs at x' at time t' in the inertial reference frame S' the event occurs at time ɣ(t' + v x'/c
^{2}) in another inertial frame S. - The proper time interval is the least time interval between two events as reckoned from any inertial reference frame.
- The proper time interval is the time interval between two events in the inertial reference frame where the events occur at the same position.
- The proper length of a rod is the length of the rod in the inertial reference frame where the rod is at rest.
- The rest reference frame for a moving object is the reference frame in which the object is at rest.
- On a spacetime diagram the units on each axis have the same scale.
- On a spacetime diagram the worldline of a particle of non-zero rest mass cannot have a gradient less than 1.