一道sat2物理题
问题描述：
一道sat2物理题
Two identical,human-looking robots are standing and facing forward in separate spaceships.Both ships are moving at 0.8c but are traveling in opposite directions,as shown above.If a person on the ship with robot A could make measurements on both robots,which of the following would the person observe to be different?
A the robot's height
B the length of the robots' feetfrom toe to heel
C the width of the robot's face
D the length of robots' legs
E the width of the robots' shoulders
答
选B
如果有图就更好了.
根据题目可以看出来物体相对的运动方向是沿着机器人脚趾头到脚跟这个方向运动的
因为速度接近于光速c,而根据相对论可以知道在物体运动速度接近光速时,与运动方向一致的轴上的长度会变化,人身边的机器人相对人是静止的,而相对人运动的机器人的脚趾头到脚跟的距离会相对变短.所以选B