1.
An attack spaceship moving towards us at 0.9 c fires a rocket at us; according to the gunner in the spaceship, the rocket moves at 0.8 c. We measure the rocket's speed as
2.
We've seen cases where different observers can't agree on the times of events, or even on the order of events. So could there be a reference frame in which you were born before your mother was born?
Choose all correct options below (unless all are incorrect):
E = mc2 applies when rest energy is converted to
4.
Which of these is the same as measured by any uniformly moving observer?
(You can check 0, 1, or 2 boxes before submitting.)
5.
Tom and Dick observe Harry zooming along in a uniformly moving spaceship. Tom observes that Harry travels 12 light-years in 13 years. Dick, who is in his own spaceship and is moving (uniformly) relative to both Tom and Harry, thinks that Harry has only traveled 6 light-years. To the nearest year, how long does Harry's trip take according to Dick? (HINT: Compute the spacetime interval for the trip.)
6.
A particle that can travel faster than light is a
7.
My (here, now) event can influence events in my... (You can check 0, 1, or 2 boxes before submitting.)
8.
If adding energy to something increases its mass, why don't we notice a cup of coffee gaining mass when we reheat it in the microwave?