A Spear 10 Meters Long Is Thrown at a Relativistic

Multiple Choice

A spear 10 meters long is thrown at a relativistic speed through a pipe that is 10 meters long (both these dimensions are measured when each is at rest) . When the spear passes through the pipe, which of the following statements best describes what is observed?

A) The spear shrinks so that the pipe completely covers it at some point.
B) The pipe shrinks so that the spear extends from both ends at some point.
C) Both shrink equally so the pipe just barely covers the spear at some point.
D) any of these, depending on the motion of the observer (moving with the spear, at rest with the pipe, etc.)
An observer fixed to the pipe would measure the mass of the spear to be greater than when at rest; an observer moving with the spear would measure the mass of the pipe to be
E) more than when at rest.
F) less than when at rest.
G) the same as when at rest.