6. The kinetic energy of an electron is 55% of its rest mass energy. Find the speed of the electron. с

6. A particle has a speed of 96% of the speed of light and a mass of 1u. The particle is unstable and its lifetime is 150 ns. It passes through a room where we stand and observe.   (a) How long do we think the lifetime of the particle is?   (b) The room is 10 m long, but how far does the particle feel as it passes?  (c) How much of the particle's total energy is rest mass?

measured by this observer to be 10 times longer than its lifetime when at rest relative to the observer? 3. The lifetime of a free neutron is 886 s. If a neutron moves with a speed of 2.9 x 108m/s relative to an observer in the lab, what does the observer measure the neutron's lifetime to be? 4. A computer in a laboratory requires 2.50 us to make a certain calcu- lation, as measured by a scientist in the lab. To someone moving past the lab at a relative speed of 0.995c, how long will the same cal- culation take? 5. The formula for length contraction gives the length of an interval on a ruler moving with velocity v relative to an observer as V1-v²/c² times the length of the same interval on a ruler at rest with respect to the observer. By what fraction is the length of a meter stick reduced if its velocity relative to you is measured to be 95 percent the speed of light? 6. If an electron is speeding down the two-mile-long Stanford Linear Accelerator at 99.98 percent the speed of light,…

8. In a proton linear accelerator, protons are accelerated to have a kinetic energy of 550 MeV. What is their relativistic momentum? (The rest mass of a proton is 1.67 x 10-27 kg.) kg.m/s 16