1. A spaceship travelling away from earth with a speed of 0.6c as measured by an observer on earth. The rocket sends back a light pulse back to earth every 10 minutes as measured by a clock in the spaceship.
How far does the spaceship travel between each light pulses as measured by: a) the observer on earth and b) someone on the spaceship?
2. An electron is moving at a constant velocity of 0.90c with respect to a lab observer X. Another observer Y is moving at a constant velocity of 0.50c with respect to X in a direction opposite to that of the electron in X's reference frame. What is the mass of the electron as measured be Y?
3. Protons are accelerated from rest through a potential difference of 8.0E8 V. Calculate as measured in the laboratory frame of reference after acceleration the proton's mass, velocity, momentum and total energy.
The Attempt at a Solution
1. a) I first found time t passed on earth between pulses and simply used d = (t)(0.6c). But it didn't work. And I haven't a clue how to do the second part.
The other ones I don't have a single clue.