# Question

One of a pair of 25-year-old twins takes a round trip through space while the other twin remains on Earth. The traveling twin moves at a speed of 0.95c for a total of 39 years, according to Earth time. Assuming that special relativity applies for the entire trip (that is, neglect accelerations at the start, end, and turnaround),

(a) What are the twins’ ages when the traveling twin returns to Earth?

(b) On the round trip, how far did the traveling twin go according to the traveling twin?

(c) On the round trip, how far did the traveling twin go according to the Earth twin? Which of your answers to parts (b) and (c) are proper lengths, if any?

(a) What are the twins’ ages when the traveling twin returns to Earth?

(b) On the round trip, how far did the traveling twin go according to the traveling twin?

(c) On the round trip, how far did the traveling twin go according to the Earth twin? Which of your answers to parts (b) and (c) are proper lengths, if any?

## Answer to relevant Questions

Alpha Centauri, a star close to our solar system, is about 4.3 light-years away. Suppose a spaceship traveled this distance at a constant speed of 0.90c relative to Earth. (a) How long did the trip take according to an ...A small airplane has an airspeed (speed with respect to air) of 200 km/h. Find the time for the airplane to travel 1000 km if there is (a) No wind, (b) A headwind of 35 km/h, and (c) A tailwind of 35 km/h. The United States uses approximately 3.0 trillion kWh of electricity annually. If 20% of this electrical energy were supplied by nuclear generating plants, how much nuclear mass would have to be converted to energy, assuming ...Phase changes require energy in the form of latent heat (Chapter 11). (a) If 1 kg of ice at 0oC is converted to water at 0oC, will the water have (1) more, (2) the same, or (3) less mass compared to the ice? Why? (b) What ...Suppose two black holes meet and “coalesce” into one larger black hole. If they each have the same mass M and Schwarzschild radius R, (a) Express the single black hole’s Schwarzschild radius as a multiple of R. (b) ...Post your question

0