I posed this question to my teacher: I have a 2 kg object and it sits at rest on the floor. The force is mass * acceleration, so it's about 20 N. Now I drop the ball from, say, 20 feet above the ground. Same mass, same acceleration, so it has the same force, 20 N; but we know the object hits much harder. If it has the same force, why does it hit harder? Am I making the assumption that force and 'how hard it hits' are equivalent statements when they really aren't? She told me it had to do with a thing called 'momentum', and we would go over it next semester (I don't want to wait that long for an explanation!). If someone could set me straight on this, I'd really appreciate it. Thanks.