Why is there a cap on the speed at which we can attain?

Question

Also, If you are traveling 1 mph under the speed of light on a train and throw a baseball in front of you at 20mph what would a viewer outside the train see?

Answer 1

The observer standing by the tracks would observe that the baseball is travelling faster than the train, but less than the speed of light.

There is an equation for the addition of velocities: see See http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/einvel.html