Alberta Diploma Exams Physics — practice by topic

1. Einstein began the theory of special relativity with two postulates. 2. The first postulate states that the laws of physics are the same in all inertial reference frames. 3. The speed of light does not double for a moving source, and mass at rest does not increase without limit. 4. Time is not identical for every observer once relative motion is involved, which is the opposite of a founding postulate. 5. So the same laws of physics in all inertial frames is correct. _Source: OpenStax Physics (CC BY 4.0), Ch 10 "Special Relativity", section 10.1 Postulates of Special Relativity_

1. An inertial reference frame is one where all objects follow Newton's first law of motion. 2. In such a frame, an object at rest stays at rest, and a moving object keeps moving at constant velocity unless a force acts on it. 3. A frame that is always accelerating would not satisfy this condition, so it is not inertial. 4. Being fixed to the sun or making light travel in circles are not part of this definition. 5. So a frame following Newton's first law is correct. _Source: OpenStax Physics (CC BY 4.0), Ch 10 "Special Relativity", section 10.1 Postulates of Special Relativity_

1. Time equals distance divided by speed, t = d divided by v. 2. Convert the distance to metres: 1.50 x 10^8 km equals 1.50 x 10^11 m. 3. Divide by the speed of light: t = 1.50 x 10^11 divided by 3.00 x 10^8. 4. Dividing gives t = 500 s, which is 8 minutes and 20 seconds. 5. 50.0 s and 125 s are too small, and 1500 s is three times too large. 6. So 500 s is correct. _Source: OpenStax Physics (CC BY 4.0), Ch 10 "Special Relativity", section 10.1 Postulates of Special Relativity_