A particle detector can be used to measure the speed of an unstable particle if the lifetime is known. Particle 'X' has mean lifetime 7 in its rest frame. Suppose 'X' particles are created in an experiment inside the detector by a nuclear reaction. If the 'X' particles leave tracks with mean length L before they decay into other particles, what is the mean speed of the 'X' particles? Express the answer in terms of the speed of light. T=282.0 ps; L= 10.5 cm;

A tau lepton is a particle that decays into a muon and two particles of negligible mass. The tau lepton has a rest mass energy of 1777 MeV, and the muon has a rest mass energy of 105.7 MeV. Suppose the tau lepton is at rest and all of the missing mass goes into the muon's kinetic energy. How fast will the muon move? (Enter your answer in terms of c to at least four significant figures.)

What is the momentum in MeV/c of an electron with a kinetic energy of 2.00 MeV?

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 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. Thank you so much!!

Particles accelerators such as the Large Hadron Collider (LHC) can accelerate particles up to tremendous energies. Suppose the LHC accelerates alpha particles (a.k.a. helium nuclei with a charge of +2e and a mass of 6.645 x 10-27 kg) with a kinetic energy of 7.5 TeV*, what would the speed of one particle be if relativistic effects** are ignored? Give your answer in units of Gm/s. *T as in Tera, for 1012. "eV" stands for "electron volt," which is a non-Sl unit of energy equal to what one electron would gain after travelling through 1V. 1eV = 1.602 x 10-19 J. **Special relativity is necessary to correctly account for the limiting speed of light, which is about 3 x 10° m/s. Note that in ignoring this effect and applying Newtonian mechanics (what you learned in Phys1210 or equivalent), you'll be getting a speed way above 0.3 Gm/s. That's just how insanely energetic the LHC is.

The dimensionless parameter γ is used frequently in relativity. As γ becomes larger and larger than 1, it means relativistic effects are becoming more and more important. A. What is γ if v = 0.28c?  B. What is γ if v = 0.53c?

A particle is traveling at 0.98c, where c is the speed of light.  According to an observer at rest, the particle is traveling a distance 5.6 meters before disintegrating. What is the lifetime of the particle as measured in the moving frame?  Express your answer in nanoseconds and keep three significant digits

A subatomic particle moves through the laboratory at 0.90c. Laboratory experimenters measure its lifetime, from creation to annihilation, to be 2.3 ps (1 ps = 1 picosecond = 10-12 s). According to the particle, how long did it live?

A beam of particles travels by at 2.0*10^8. At this speed you measure them to live 5.00* 10^6  sec, before decaying. What is the particle's life time at rest?

An alpha particle is the nucleus of a He-4 atom and has a rest mass of 3727.38 MeV/c2. How much energy is required to accelerate an alpha particle from rest to 0.6c? What is the momentum of the alpha particle once it reaches this speed? Would more, less or the same amount of energy be required to accelerate a proton from rest to this speed?