Question

if you and a friend are on a train throwing a ball back and fourth to each other at 10 km/h and the train is traveling at 40km/h , how fast is the ball traveling to you and how fast is the ball traveling to your friend ?

Answer 1

and if you have another friend who is standing near the train tracks as you pass by, how fast does that friend see the ball traveling ?

Answer 2

This is known as the principal of relativity.
When you're on a train, you don't realise that you're moving (unless the train is speeding up/slowing down). From inside the train, all objects appear to be moving at "regular speed". Something set on a table won't just slide off, and throwing something would be just the same as in a non-moving environment.
From outside the train, everything inside the train appears to be moving. A person sitting down would be whizzing past at the same speed as the train. To find what the velocity looks like from the outside, you need to add the velocity of the train to the apparent velocity of the object from inside the train.

Answer 3

haaaa beautiful :) , I just answered a similar but a little easier question from someone. Her question was a train was crossing a bridge at 100mph and a man was walking back the other way at 5mph... how fast was the man moving across the bridge ? = 25mph.

Answer 4

i mean 95mph :)