According to Newton's third law, to each action there is an equal and opposite reaction, which means that no matter how heavy is the object, if I give it X amount of force, it will give that force back to me. However, if I were standing on top of a skateboard and I throw a bowling ball with X amount of force, it will push me to the back more than if I threw something really light like a golf ball with that same force.
Why is that?
[Physics] Why do heavier objects provide more reaction force
accelerationforcesnewtonian-mechanics
Best Answer
Suppose we have an object of mass $m$. You stand on a skateboard and throw that object as hard as you can. Suppose your arm can put out a maximum force of $F_\text{max}$.
When you push the object with your maximum force, its acceleration is $a = F_\text{max}/m$. The position of the object as a function of time during this acceleration is the usual
$$x = \frac{1}{2} a t^2 \, .$$
Your arm has only a certain length $L$ so you can only apply this force and get the object to experience that acceleration over a distance $L$. Therefore, the maximum time over which you can push the object is
$$t = \sqrt{2L / a} \, .$$
The final momentum of the bowling ball is therefore
$$p = F_\text{max} t = F_\text{max} \sqrt{\frac{2L}{a}} = \sqrt{2 L F_\text{max} m} \, . $$
So you see, the amount of momentum you can impart to an object goes proportional with the square root of that object's mass, the force you can exert, and the length of your arm.
Newton's action-reaction law says that the force exerted by you on the ball is equal to the force exerted by the ball on you. Note, of course, that these forces are exerted over equal amounts of time, so the thing that's really equal in the end is the momentum imparted onto you and the ball (in opposite directions). Since we see that the momentum you can impart on the ball increases with increasing ball mass, then the momentum exerted on you also increases with increasing ball mass.
Intuitively, this is all just saying that when you throw a golf ball, it's so light that it leaves your hand before it's had a chance to push back on you very much.