Einstein’s First Postulate Suppose you are on a train car with no windows, no means of observation of or communication with the outside world… Would you be able to tell whether you were at rest or moving with constant velocity? (Constant velocity means constant speed and constant direction) a)Yes b) No

Einstein’s First Postulate Suppose you are on a train car with no windows, no means of observation of or communication with the outside world… Would you be able to tell whether you were at rest or moving with acceleration (speeding up, slowing down, turning) a)Yes b) No

Equivalence Principle Suppose you are on a train car with no windows, no means of observation of or communication with the outside world… Would you be able to tell whether you were moving with acceleration (speeding up, slowing down, turning) or in a gravitational field a)Yes b) No