How big is Belgium? :roll:
BMB
P.S. Found these 2 letters in
www.nrich.maths.org.uk. How sad am I.
:twisted:
1. Imagine a fly above a train track. A train comes towards it and whilst they are both moving towards each other they collide. The fly is accelerated in the direction of movement of the train.
The fly has now reversed in direction. Its velocity must have passed through 0 i.e. from -ve to +ve direction. The collision is totally inelastic so they now share the same velocity. So when the fly's velocity is 0 so is the trains! The fly, has stopped the train (instantly)!
2. I'm sorry but no. The fly does not stop the train, if the train has stopped it must accelerate back to its previous speed, if it is only stopped for an instant there must be infinite acceleration. This is a feat that can only happen on poorly drawn graphs, never reality, the fly has almost infinite acceleration but not quite, there is an unnoticable duration of change of speed of the fly. There is an unnoticable change in the trains speed, yes, and the fly for an instant does stop. But this is at the point of collision, they only share the same speed after the point of collision. I might seem to be bawling in your face (I suppose it depends on how you read it), but I'd hate to think you'd ruin your chances for a decent grade on the basis of one simple misunderstanding. I hope i've set things straight.
The reason the train does stop is because :
The fly hits the train in an instant, during this time period the train does not move, so how can we measure its speed.
Flies squash into a nice mess when they hit the train so they don't behave as true particles.
