PHYS 1112
Chapter 26 Problems

Conceptual Questions

1. What is the one measurement that two observers will always agree upon, no matter what their frame of reference is?
2. Why is it impossible for any matter to be moving at the speed of light?

Selected Problems $$

1. An astronaut at rest on Earth has a heartbeat rate of 70 beats/minute. When the astronaut is travelling in a spaceship at .90c, what will this rate be as measured by (a) an observer also in the ship and (b) an observer at rest on the Earth?
2. Calculate the momentum of an electron moving with a speed of (a) .010c, (b) .50c, (c) .90c.
3. At low speeds, a charged object in a magnetic field moves in a circular path of radius r = mv/qB. If an electron moves in an orbit of radius 10 cm with a speed of 1.0 x 10⁵ m/s, what will the radius be when its speed is .96c?
4. How fast must you be moving toward a red light (l = 650 nm) for it to appear green (l = 525 nm)?

Solutions

If you find an error in these, or just have a comment, send an e-mail message to jpratte@kennesaw.edu