Ok, I think you guys have cleared it up for me, thanks so much :D :D
I was confused, like you have pointed out, with the distinction between measuring the distance between the two lightning strikes, and measuring the length of the train.
Thanks again :)
I'm confused about what exactly this is, and wikipedia hasn't really helped.
It says here the proper length is the length of an object in it's rest frame.
Yet it says here that "the proper length between two spacelike-separated events is the distance between the two events, as measured in an...
Woooooaahhh ok the images were huge. I've spoiler tagged them but they're still massive. Can someone tell me how to resize please? (sorry this is my first thread I'm a noob)
EDIT: ok well spoiler tags achieved nothing. What use are spoiler tags when they don't hide whatever you put in them??
Homework Statement
An open-topped railway wagon of mass M is rolling freely along straight level frictionless track at a constant velocity v0. At time t=0 the wagon enters a heavy rain shower and starts to collect rainwater. The rain falls vertically. As a consequence the wagons mass increases...