this post was submitted on 10 Apr 2024
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This is true on earth. If you have objects of the same shape and different weights and you drop them from high enough to reach terminal velocity, the heavier one will have a high terminal velocity through air and reach the ground faster.
The "in a vacuum" thing is where this goes wrong, but I don't think homeboy really knew about space or vacuums.
no. Gravity is consistently pulling at 9.85m/s regardless of the size or density in an object.
Terminal velocity is reference to the air resistance and buoyancy affect on an object in freefall. This has nothing to do with the mass or size of the object, but it's air resistance.
https://openstax.org/books/college-physics-2e/pages/2-7-falling-objects
Gravity is (mostly) consistent across the planet and will always pull the same force regardless of the object in question.
Any object with mass has gravity
Say the moon was falling to earth
Would the earth not be drawn in space towards the moon as it fell?
The moon and earth would collide at a rate faster than 9.85m/s?
They actually are. The Moon technically doesn't orbit the earth, but a point near earth, that earth does as well. Its momentum that prevents the moon from crashing to earth, and it's gravity that prevents it from flying off into space.
https://en.wikipedia.org/wiki/Barycenter_(astronomy)
Because the earth is so much more masive than the moon, the Barycenter of the gravity point is not the centre of the earth itself.
And another interesting fact: The moon's momentum is slightly greater than that of the earth's gravity, causing the moon to very very slowly move further away from Earth (About 3.7cm a year).
but it's these momentums and gravitational forces that keep the moon orbiting (Orbital mechanics is fucking fascinating as fuck)
But what would happen if two bodies collided that are large? The force of impact would be the combined momentum of the two items as you believe. It is believed this is what actually formed our moon as early formation of the planets saw two planet sized bodies impact like you describe, the resulting force spun enough matter to form the moon (Mineral inspection of moon rock shows it contains the same isotopes as earth, which is rare if the moon formed on it's own).
pint to remember; A bodies gravitational force is based on it's mass. Larger mass items have more gravitational force. Because fo that, While gravity is 9.85m/s on earth, it would be different on every piece of matter. Even a single atom has it's own gravity force, albeit very low. Your "gravity" force on the moon is not 9.85 but a speed based on it's own mass. This is why you would be "heavier" on earth than say the moon or mars, despite your mass not changing. the planetary body mass affects gravity.
ANOTHER fun fact. Gravity and mass affects time as well. Objects closer to a center of mass operate slower than those further away. Satellites for example actually move faster in time than we do on earth. GPS for example overcame this by programming to check real earth time frequently.