Okay dumb question (sorry), but I thought acceleration due to gravity was constant relative to mass, so shouldn't the red and the green ball fall at the same rate?
The whole "feather and bowling ball dropped in a vacuum" experiment, right?
The whole "feather and bowling ball dropped in a vacuum" experiment, right?
But that difference is not really measurable and probably barely calculable - though I'm sure someone on here may do that.
If you dropped them side-by-side the difference would require factoring in the curvature of the Earth and would really be way below anything you might measure... If you drop them in series then yes that does have another effect... the actual acceleration should be like g(1+m/M) instead of just g, so if a ball is 0.6 kg and Earth is 6e24 kg the fall time goes like √(2D/g) and so for a 10s (500 m) freefall in vacuum it changes the time by 0.5 yoctoseconds? Way smaller than any clock accuracy as far as I know...
No the real inaccuracy is that the drag force in air will scale like the square of the velocity,
m dv/dt = m g – ½ ρ A v² c
dv/dt = g – g (v/U)²
v(t) = U tanh(g t/U)
So that's my pet peeve: The two things on Earth should fall side-by-side in tandem at first, then slowly the tennis ball should lag behind! That's not what we see in this simulation, unfortunately.
GDoc: https://docs.google.com/spreadsheets/d/1AnUeQ0RR7a5GA6Nrtef7...
I didn't realize the "Why balls fall at all" was a button.
Predefined things you can drop are basketball, bowling_ball, massive_sphere, dense_sphere, lead_sphere, pine_sphere, pingpong_ball, ant, rat, cat, person, and phone. You can add other things if you know their mass, cross sectional area, and coefficient of drag.
Yes, you're partially right...if we drop both balls on Moon, they'll fall at the same time. Because there's (almost) no air on the Moon. The ball with less mass has less force of gravity to fight with air resistance on the Earth. Therefore, it falls slower.
Maybe this video can help to visualize: https://www.youtube.com/watch?v=Esa0kKECZvM
Even that is not correct. Air resistance is proportional to cross-section, and gravity is proportional to mass. A ball with less mass but much less cross section will fall faster. It has less "force of gravity", but it has much less air resistance. In other words, a marble will fall faster than a basketball when accounting for air resistance.
Note that the animation is inaccurate in any case because (assuming constant air density) the velocity of a falling ball will never decrease (until it hits the surface) if it started stationary.