what will happen if i throw a baseball to a friend while i am standing on a skateboard.?

Question

how does the 3rd law of motion has to do with it

Answer 1

You will skate away from the direction that you threw the ball.

For ever action there is an opposite and equal reaction: the 3rd law.

According to Wikipedia: http://en.wikipedia.org/wiki/Newton%27s_Laws_of_Motion
"Briefly stated, the three laws are:

1. An object will remain at rest, or continue to move at a constant velocity, unless a net force acts on it.
2. Net force on an object is equal to its mass multiplied by its acceleration.
3. For every force acting on an object, the object will exert an equal, yet opposite, force on its cause. "

So the force that put into throwing that ball will then be exerted on you and the skateboard. If it is enough to overcome inertia then you will roll a little backwards. Try it and prove that it happens.

Answer 2

Since you exert a force on the basketball, Newton's 3rd law says that the basketball exerts a force back on you. This force should send you slightly backwards. Your acceleration, though, would be less than that of the basketball because even though the forces are the same, your masses are different (F=ma),