Special Relativity - Length Contraction

A student is travelling at 0.7 c to a distant planet that is stationary relative to earth. They caculate the journey based on their speed and travel distance and find that the journey was 14 lightyears (8.23E18 miles). What distance is the journey from the perspective of the students friends and family back on earth.

• 19.6 Ly

• 20.5 Ly

• 30.9 Ly

• 36.5 Ly

A student traveling at 0.7c has a spaceship which is 250 meters long according to his measurement, how long would the ship have appeared to an observer back on earth.

• 178.5 m

• 153.2 m

• 139.6 m

• 85.6 m

A space alien is planning a trip to invade earth. He knows that earth is 7 light years (4.115E13 miles) away from him, when he is stationary on his planet( which is stationary with respect to earth). How long will his journey appear to him when he reaches his top speed of 0.95c?

• 2.19 ly

• 4.72 ly

• 0.89 ly

• 5.63 ly

If the space alien measures his spaceship to be 100 meters while hes on the planet, how long will it look to him once he has reached his top speed.

• 19 Meters

• 83 Meters

• 120 meters

• 100 meters

What is the definition of length contraction?

• The change in color of an object that is moving relative to an observer

• The decrease in width of an object that is moving relative to an observer

• The apparent decrease in length of an object that is moving relative to an observer

• The increase in length of an object that is moving relative to an observer

In which direction does the contraction of length take place?

• In a random direction

• In the direction of travel

• In all directions

• In the opposite direction of travel

What is the proper length as measured by an observer?

• The length measured by an observer in a different frame of reference

• The length measured by an observer in the same frame of reference as the event

• The length measured by an observer standing still

• The length measured by an observer moving relative to the object

What is the equation for length contraction using the Lorentz factor gamma?

• l prime = l / gamma

• l prime = l * gamma

• l prime = l - gamma

• l prime = l + gamma

What happens to the length of an object as it approaches the speed of light?

• It decreases

• It remains the same

• It becomes infinite

• It increases

What is the relativistic length as measured by an observer in a different frame of reference to the event?

• l prime

• l dash

• l observer

• l relativistic