Originally Posted by
dubbleyew eight
there was an experiment many years ago where objects were dropped off the Eiffel tower to explore the effect. you are wrong.
Well, no, he's not wrong. I don't know about the Eiffel tower experiment, but Galileo is famously (and perhaps apocryphally) credited with doing the same thing at the Tower of Pisa. Some accounts have the balls falling at the same speed, other accounts have the heavier ball falling perceptibly faster.
In either case, it doesn't matter, the experiment was to test the (then) current theory of "Natural Motion" concocted by Aristotle which claimed that the speed of a falling object is proportional to it's mass. And even if the denser ball fell slightly faster, it was still obvious that the difference between the two was not proportional to the respective mass differences.
Originally Posted by
dubbleyew eight
you don't get any more influence exerted on the concrete ball.
well, yeah, actually you do. The force of gravity on an object is proportional to it's mass. The basketball filled with air is about .6kg while the one filled with concrete will have a mass of 17 kg. So the force of gravity (in round numbers) near the earth's surface will be 6 newtons on the air ball, and 170 newtons on the concrete ball.
In the absence of any other force, the acceleration will be identical (because the force is proportional to the mass) but the balls are falling thru the atmosphere, not a vacuum. There is also drag to consider.
OK, forget weight for a moment. you have two objects moving through the same air. they have identical drag coefficients and identical frontal areas, and identical wetted area. Aerodynamically, they are identical. One has 6 newtons of force propelling it thru the air, and the other has 170 newtons of force propelling it through the air.
Which will travel faster thru the air?
It should be obvious that the object with 170 newtons propulsive force will travel faster than the one with 6 newtons.
It's the same with falling objects. As the balls fall faster, the drag begins to predominate over inertia, and more and more of the force of gravity is counteracted by the drag and less of it accelerates the balls. And the ball that has the least force will accelerate less than the ball with more force.
Ultimately both balls will reach their terminal velocity*, and the terminal velocity of the concrete ball will be much higher than the terminal velocity of the air filled ball.
*Dangerous territory when dealing with a poor understanding of physics. There is a popular misconception that there is some single "terminal velocity" for any and all falling objects This ain't true. Not even close. Every object has it's own terminal velocity determined by it's density and aerodynamic properties. A feather has a very low terminal velocity. Doesn't matter how high you let it fall, it ain't falling any faster. A high penetration aerial bomb on the other hand has a very high terminal velocity. There are bombs which will exceed the speed of sound while in a free fall. This is because they have a lot of mass and have a very low drag coefficient. (lots of gravitational force vs. not much drag force) The terminal velocity of a skydiver in free fall is somewhere between a feather and a bunker buster bomb. In fact, different individual skydivers will have different terminal velocities depending on their technique.