Who said objects fall at the same rate

Try this. Take a baseball and a ping pong ball and drop them together. It will probably be closer than you think but the heavier baseball will indeed hit the ground first. Your initial thoughts would be confirmed. Heavier things do indeed fall faster.

Here is the first classic example. This is a bowling ball and a basketball dropped from the same height. Normally, I hold these two balls up in a classroom and ask students which will hit the ground first. I never actually drop them because dropping a bowling ball on the ground from above your head might not be such a great idea. However, it does get the students excited that I might actually drop them.

This year, the students convinced me to actually drop them. We went outside so I could drop them in the grass. Here are two videos that students recorded. There is a bonus experiment afterwards which I will describe bellow. View Iframe URL. These two objects clearly have different mass but they fall with the same acceleration. I guess I should point out one more thing about falling objects. If you were to measure the position of these balls as they fall, they do not fall with a constant speed.

Instead, they fall with a constant acceleration. That is to say that as they fall, the speed increases. For these two objects, they hit the ground at the same time because they both start from rest and both have the same acceleration.

Here is another example that you can try yourself. Take two sheets of plain paper. They have the same mass, right? Roughly speaking, the way masses move is solely dependent on the local properties of the gravitational field, independently of their mass. This observation lead Einstein to the formulation of the Equivalence Principle , and is the reason we think of gravitational force as a reflection of the local curvature of space time.

This provide a way of measuring the ratio in the lab. The result is that this number is one with an accuracy of 1 in 20 million. So we are tempted to believed that indeed inertial mass is the same a gravitational mass and consequently, that all masses are affected the same way by gravity, or said in other words, that gravity is an emergent property of the local geometry of spacetime. No, he is not right. The reason is that the gravitational mass of an object is equal to its inertial mass.

For all we know this is exact and there is no approximation involved besides the assumption of no air resistance. As you can see, this force depends on the mass of the object and will be much bigger for the cannon ball than for the feather. Just put a cannon ball on your head and you will feel the difference compared to having a feather on your head. Miraculously, for reasons unknown, it turns out that these two effects just cancel each other such that the acceleration is the same for heavier and lighter objects.

So Galileo's report was pretty skimpy. He seems to have dropped different balls from a tower. But what weights? What tower? We can be pretty sure it was the Leaning Tower of Pisa.

But we end up doubting whether or not he really did the experiment. Maybe he just reported what he thought should have happened. One result of the experiment surprised Galileo, and one surprises us. Galileo found that the heavy ball hit the ground first, but only by a little bit.

Except for a small difference caused by air resistance, both balls reached nearly the same speed. And that surprised him.

John Philoponus, in the 6th century, is said to have performed the "Tower of Pisa" experiment except not with that tower ; the Stanford Encyclopedia of Philosophy has an extensive article on him, and the Wikipedia entry has this quote from his works: But this [view of Aristotle] is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument.

Improve this answer. Michael Weiss Michael Weiss 4, 18 18 silver badges 45 45 bronze badges. Interesting references - I'm surprised I hadn't heard of Philoponus before, and it makes sense that Galileo referred to him a lot. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. Featured on Meta.