Muons created in the upper atmosphere can travel towards the Earth’s surface at speeds
close to the speed of light. Changes to the mass and average lifetime of the muons can
then be observed.
Which row of the table describes these changes when muons travel at speeds close to
the speed of light?
Mass Average lifetime
A increases increases
B increases decreases
C decreases increases
D decreases decreases
(Total for Question 4 = 1 mark)