Question

a train moving near the speed of light enters a tunnel. according to a person standing in the middle of the tunnel, the back end of the train enters the tunnel first. which of the following is a possible explanation for this observation? a. length expansion. b. time dilation. c. mass increase. d. anomalous dispersion. e. motion symmetry. your response history: 1. incorrect. your answer: a. length expansion. score: 0/0.21 you may change your answer and resubmit.

Explanation:

In special relativity, when an object moves at high - speeds (near the speed of light), time dilation occurs. Time passes more slowly for the moving object relative to a stationary observer. Length contraction (not expansion) occurs where the length of the moving object appears shorter in the direction of motion. Mass increases as the object approaches the speed of light. Motion symmetry is a related concept but not the main effect here. Anomalous dispersion is unrelated to this high - speed motion scenario.

Answer:

C. mass increase.