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A dude I'm discussing momentum and kinetic energy with says this:

"

*Place two masses in deep space, the only gravitational attraction is from each other.*

One of the masses is ten kilograms and the other is one kilogram.

From Newton's Third Law we know that the mutual attraction is equal in both directions.

From F = ma we know that the acceleration of the one kilogram will be ten times greater than the acceleration of the 10 kilograms.

After a period of time the one kilogram will be moving 10 times faster than the 10 kilograms. When the one kilogram is moving one meter per second the 10 kilograms will be moving .1m/sec.

Then ½ *10kg *.1 m/sec * .1 m/sec = .05 joules

And ½ * 1 kg * 1 m/sec* 1 m/sec = .5 joules

Energy is not conserved."

One of the masses is ten kilograms and the other is one kilogram.

From Newton's Third Law we know that the mutual attraction is equal in both directions.

From F = ma we know that the acceleration of the one kilogram will be ten times greater than the acceleration of the 10 kilograms.

After a period of time the one kilogram will be moving 10 times faster than the 10 kilograms. When the one kilogram is moving one meter per second the 10 kilograms will be moving .1m/sec.

Then ½ *10kg *.1 m/sec * .1 m/sec = .05 joules

And ½ * 1 kg * 1 m/sec* 1 m/sec = .5 joules

Energy is not conserved

This guy say that if you have a 10kg steel ball, here at earth, that is pushed into motion at 0.1m/s and spend all its momentum to put a 1kg. steel ball into motion, the 1kg ball would have a velocity of 1m/s, but with that mass and velocity, the kinetic energy is 10 times greater than the kinetic energy of the 10kg ball before impact.

Why does he say that energy isn't conserved? I assume it must be a misunderstanding in how he calculate the results, even he is right about conservation of momentum.

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