Dear PF Forum, I am wondering about object fall speed. Aristotle had formulated that object drops relative to their mass. But Galileo(?) suggested the other way when he dropped object with different mass (supposedly from Pisa). And astronaut had demonstrated on the moon that object regardless of their mass drop at the same speed. Okay, this is Newton, right? Considering this. Two objects. A. A pebble B. 1000 tonnes sphere rock. If they are dropped at, say, 49 KM above ground, assuming earth has no atmosphere, they will reach ground at 100 seconds, is that true? What about A (a pebble) and J (a very massive sphere rock, say, at Jupiter mass) are dropped at 49 KM, will A and J fall at the same SPEED? Or, the earth will actually FALL to J at 24.79M2? Was Aristotle right? So, back to the original question. (A) A pebble and (B) 1000 tonnes rock drop at 49 KM, will B reach ground in 99.99999.... seconds? Thanks for any answer.