1. The problem statement, all variables and given/known data Does the speed of a ball increase, decrease or remain the same once it leaves the hand as it being thrown horizontally? 2. Relevant equations Law of conservation of momentum 3. The attempt at a solution According to my calculations, it increases as momentum is transferred from the arm/hand to the ball. I feel it is right though according to a friend of mine it is wrong as the speed should be unaltered according to Newton's 1st law. Who of us is right?