An object is moving a speed 5c/10, where c is the speed of light.  Calculate gamma (γ).

A particle has γ=18,399. a)Calculate c-v in m/s. (I would have asked for 1 - v/c, making the answer dimensionless, but the system doesn't seem to take numbers that small. Gamma is chosen to make the particle extremely close to the speed of light.) If your calculator gives problems, you might want to solve the appropriate equation for c-v or c(1 - v/c) and use an approximation. b) In the previous problem, in a race to the moon, by 3/4ths the distance, light is one or ten meters ahead of the particle. We routinely approximate mass as zero, gamma as infinite, and speed as the speed of light. ("Massless particles" -- gamma and m have to be eliminated from the expressions. Light is a true massless particle.) If a massless particle has momentum 1,739 MeV/c, calculate its energy in MeV.

A star is 16.6 light-years from Earth. Part A How long would it take a spacecraft traveling 0.950c to reach that star as measured by observer on Earth? tEarth 17.5 years Submit ✓ Correct Correct answer is shown. Your answer 17.47 years was either rounded differently or used a different number of significant figures than required for this part. Part B How long would it take a spacecraft traveling 0.950c to reach that star as measured by observer on the spacecraft? t = 5.46 years Submit Part C Previous Answers Correct What is the distance traveled according to observers on the spacecraft? 15.18 light-years Previous Answers Submit Previous Answers Part D V = Correct What will the spacecraft occupants compute their speed to be from the results of part B and part C? 3.29 IVE ΑΣΦ Submit Previous Answers Request Answer ? X Incorrect; Try Again; 4 attempts remaining •C

For an astronaut traveling to a star 10 lightyears away at v=0.99c  and returning, spending negligible amount of time at the destination, describe the journey as the astronaut would observe it. In particular, describe what the astronaut would observe as happening on Earth during the journey