8. A particle has a kinetic energy of 62 MeV and a momentum of 335 MeV/c. Find its mass (in MeV/c2) and speed (as a fraction of c). 9. An observer detects two explosions, one that occurs near her at a certain time and another that occurs 2.00 ms later 100 km away. Another observer finds that the two explosions occur at the same place. What time interval separates the explosions to the second observer? 10. A spacecraft moving in the +x direction receives a light signal from a source in the xy plane. In the reference frame of the fixed stars, the speed of the spacecraft is v and the signal arrives at an angle e to the axis of the spacecraft. (a) With the help of the Lorentz transformation find the angle e' at which the signal arrives in the reference frame of the space- craft. (b) What would you conclude from this result about the view of the stars from a porthole on the side of the spacecraft?