# Shared Flashcard Set

## Details

Chapter 15: Special Relativity: Space and Time Questions
Chapter 15: Special Relativity: Space and Time Questions
24
Physics
11th Grade
12/29/2011

## Cards Return to Set Details

Term
 Einstein concluded that if an _________ was traveling near the speed of light, he would measure the light moving away from him at c, 300,000 km/s.
Definition
 observer
Term
 All the laws of physics are the same in all ______________ moving frames of reference.
Definition
 uniformly First Postulate of Special Relativity
Term
 A spaceship needs an object to ____________ its speed.
Definition
 measure
Term
 A space ship can/cannot measure its speed relative to empty space.
Definition
 cannot
Term
 All ___________ of ____________ are arbitrary.
Definition
 framesreference
Term
 Einstein reasoned that the constancy of the _____________ unifies time and space.
Definition
 speed of light
Term
 What is speed?
Definition
 Amount of space traveled compared to the time of travel. Speed = space/time
Term
 _______________ can vary the speed of light in empty space?
Definition
 Nothing
Term
 If the speed of a baseball were constant and if it were thrown at you at 5 m/s. At what speed do you catch the baseball?
Definition
 5 m/s
Term
 If the speed of a baseball were constant and if it were thrown at you at 5 m/s from a truck traveling away from you at 60 m/s. At what speed do you catch the baseball?
Definition
 55m/s
Term
 If the speed of a baseball were constant and it were thrown at you at 5 m/s from a truck traveling toward you at 60 m/s, what speed do you catch the baseball?
Definition
 65m/s
Term
 The speed of common objects is _____________.
Definition
 relative
Term
 From the frame of reference of the photon. How long does it take you to travel from one end of the universe to the other?
Definition
 The journey takes no time. Since you are going the speed of light, you are not traveling through time, you are only traveling through space.
Term
 Does light travel through space or time?
Definition
 Light only travels through space. It never travels through time.
Term
 If you could travel at the speed of light, would you travel through space or time?
Definition
 All of your travel would be through space-you would not travel through time.
Term
 When you walk, do you travel through space or time?
Definition
 When you walk you travel both through space and time, but mostly through time.
Term
 When you stand still are you traveling through space or time?
Definition
 When you stand still, all your travel is through time.
Term
 Is time an absolute quantity?
Definition
 No. Time dilation. The spaceship example shows that time is not absolute
Term
 Define: Clock
Definition
 Any device that measures periodic intervals
Term
 If a flashing clock is in a space ship moving close to C. What does the clock look like to the people on the ship?
Definition
 It is the correct time, moving at the correct intervals
Term
 If a flashing clock is in a spaceship moving close to C. What does the clock look like to someone outside the ship?
Definition
 The clock looks slow
Term
 Alpha Centauri is 4 light years away. How long, traveling close to C, does it take you to go there and back?
Definition
 Not long. If you go at close to C, with time dilation, you are traveling through space, not time.
Term
 Alpha Centauri is 4 light years away. How long will it take a person to get there and back according to a person on Earth?
Definition
 8 years. If the traveler goes close to C, in Earthâ€™s frame reference it will take 4 years to get there and 4 years to get back.
Term
 A person moving close to C can keep jumping into the future when they come back to Earth. Can they go back to the past?
Definition
 No. Time only travels one way-forward.
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