In a muon decay experiment as a verification of time dilation, the muons move in the lab with a momentum of 3190 mev/c. find the dilated lifetime in the laboratory frame. (the proper lifetime is 2.198 /is. the mass of a muon is 105.7 mev/c^2.)

It's time for santa to deliver his presents. assuming he delivers presents all over the world, he has to travel about 75,000,000 miles. if he travels east to west, he can use the time zones to make christmas day last 31 hours. what speed, in miles per hour, must santa fly to get all of his presents delivered?