19th June 2005, 12:18 PM
No.
I'm surprised they never taught you this in school, seriously. Not saying anything bad about you, but about whatever school dropped the ball here (or, didn't in the case of not showing this to you directly with an easy test). This is newtonian stuff here.
Yes, you can push yourself off the floor, if that's where you were when it started falling, and float in the air. This is because both you and the elevator are falling at the same speed.
To confirm this for yourself, that two objects of differing weights fall at the same speed, test it out. For this test I suggest you use a heavy object like a bowling ball or a rollerskate, and a light object like a crumpled up piece of paper (it must be crumpled because if it is flat, wind resistance will slow it down and cause a lot of odd movement besides). Now, to complete this small test, simply hold your arms out at the same height, and drop both objects at the same time. You'll notice both strike the ground at the same time. Now, in lighter gravity, both objects may fall slower, and in heavier they may fall faster, but they will still both hit at the same time. Also, yes, a falling object accelerates over time (the reason why dropping stuff from higher up is more dangerous than from lower) but again, the rate of accelerationg and the speed of the initial drop is not relevant to the weight of what is being dropped.
This is key.
Now, for this second test to prove my point, you will need an object you may not have. You will need a heavy but clear and solid object. For example, perhaps a goldfish bowl or a transparent hamster ball. The second thing you will need is a lighter object to put inside of it. The thing that will make this experiment tought is that you will actually have to hold this second object INSIDE the first, near the middle, and let go of both at the same time without your wrist or hand accidentally hitting the rim of the object. I suggest holding the opening straight up.
Now then, if you can manage to do it, drop both at the same time in this configuration. You will notice that, again, they both fall at the same rate. You will also notice that the small object inside, because it falls at the same rate, is not drawn towards the floor of the container. For that to happen, it would need to fall at a faster rate. So, until the large object is instantly slowed down by the ground, the ball is effectively weightless.
You can do this by direct experimentation. It won't be super accurate, but it will show within what means you have that I'm not just full of it.
To go further with visual examples, you've seen sky divers on TV correct? They dive out of planes and before deploying their parachute, they can pretty much act just like a weightless person. A weightless person with a planet heading towards them at an alarming speed. Now, the second the parachute is pulled, they are suddenly pulled down because they are being restricted from free fall. Now, their movement is reduced by a bunch.
At any rate, imagine this same sky diver falling, but inside a massive sphere that is also falling with them (imagine the outside is aerodynamic enough that the atmosphere isn't slowing the sphere down to a massive degree). Since they are falling at the same rate, the sky diver will see themselves basically hovering in the middle of the sphere, and with the sphere holding in all that air like that, the upgoing wind is gone too, so if the parachute is deployed, it will behave like a parachute in a spaceship in orbit.
Now for one final point to really drive it home. It's my biggest argument really. They actually TRAIN for weightless environments by flying people really high into the sky, diving the plane at the ground for a minute, levelling off, flying back up, and diving again for a minute. They film this sort of thing all the time. When they are in the free fall, everyone is able to do everything one can do in orbit. Things like making bubbles of liquid float about or scatter M&Ms and jump after them eating them from the air.
And just as a reminder, if you were standing still in the orbit plane most satellites orbit in (reletive to the earth, everything's reletive), you would just fall straight to the planet. You have to actually be shooting by the planet to orbit. An orbit consists of you moving fast enough past the planet to avoid being pulled straight down to your death, but not so fast that you overcome gravity completely. Gravity at that point is only 20% of what it is at sea level. At this level, gravity is still felt unless you are in a state of free fall, which is what an orbit actually is. An orbit consists of you literally falling AROUND the planet. As you go around, you form an ellipse, not a perfect circle. This ellipse is actually a required part. In the further edges of the ellipse, you are slowing down a bit so you are pulled a little more towards the planet. In the closer edges of the ellipse, you are falling faster giving you the energy you need to shoot out to a further edge.
At any rate, I think I've explained this well enough, and it's explained further over at badastronomy.com (I'll link to it again because I have the nagging feeling you didn't read various bits regarding gravity at that site).
I'm surprised they never taught you this in school, seriously. Not saying anything bad about you, but about whatever school dropped the ball here (or, didn't in the case of not showing this to you directly with an easy test). This is newtonian stuff here.
Yes, you can push yourself off the floor, if that's where you were when it started falling, and float in the air. This is because both you and the elevator are falling at the same speed.
To confirm this for yourself, that two objects of differing weights fall at the same speed, test it out. For this test I suggest you use a heavy object like a bowling ball or a rollerskate, and a light object like a crumpled up piece of paper (it must be crumpled because if it is flat, wind resistance will slow it down and cause a lot of odd movement besides). Now, to complete this small test, simply hold your arms out at the same height, and drop both objects at the same time. You'll notice both strike the ground at the same time. Now, in lighter gravity, both objects may fall slower, and in heavier they may fall faster, but they will still both hit at the same time. Also, yes, a falling object accelerates over time (the reason why dropping stuff from higher up is more dangerous than from lower) but again, the rate of accelerationg and the speed of the initial drop is not relevant to the weight of what is being dropped.
This is key.
Now, for this second test to prove my point, you will need an object you may not have. You will need a heavy but clear and solid object. For example, perhaps a goldfish bowl or a transparent hamster ball. The second thing you will need is a lighter object to put inside of it. The thing that will make this experiment tought is that you will actually have to hold this second object INSIDE the first, near the middle, and let go of both at the same time without your wrist or hand accidentally hitting the rim of the object. I suggest holding the opening straight up.
Now then, if you can manage to do it, drop both at the same time in this configuration. You will notice that, again, they both fall at the same rate. You will also notice that the small object inside, because it falls at the same rate, is not drawn towards the floor of the container. For that to happen, it would need to fall at a faster rate. So, until the large object is instantly slowed down by the ground, the ball is effectively weightless.
You can do this by direct experimentation. It won't be super accurate, but it will show within what means you have that I'm not just full of it.
To go further with visual examples, you've seen sky divers on TV correct? They dive out of planes and before deploying their parachute, they can pretty much act just like a weightless person. A weightless person with a planet heading towards them at an alarming speed. Now, the second the parachute is pulled, they are suddenly pulled down because they are being restricted from free fall. Now, their movement is reduced by a bunch.
At any rate, imagine this same sky diver falling, but inside a massive sphere that is also falling with them (imagine the outside is aerodynamic enough that the atmosphere isn't slowing the sphere down to a massive degree). Since they are falling at the same rate, the sky diver will see themselves basically hovering in the middle of the sphere, and with the sphere holding in all that air like that, the upgoing wind is gone too, so if the parachute is deployed, it will behave like a parachute in a spaceship in orbit.
Now for one final point to really drive it home. It's my biggest argument really. They actually TRAIN for weightless environments by flying people really high into the sky, diving the plane at the ground for a minute, levelling off, flying back up, and diving again for a minute. They film this sort of thing all the time. When they are in the free fall, everyone is able to do everything one can do in orbit. Things like making bubbles of liquid float about or scatter M&Ms and jump after them eating them from the air.
And just as a reminder, if you were standing still in the orbit plane most satellites orbit in (reletive to the earth, everything's reletive), you would just fall straight to the planet. You have to actually be shooting by the planet to orbit. An orbit consists of you moving fast enough past the planet to avoid being pulled straight down to your death, but not so fast that you overcome gravity completely. Gravity at that point is only 20% of what it is at sea level. At this level, gravity is still felt unless you are in a state of free fall, which is what an orbit actually is. An orbit consists of you literally falling AROUND the planet. As you go around, you form an ellipse, not a perfect circle. This ellipse is actually a required part. In the further edges of the ellipse, you are slowing down a bit so you are pulled a little more towards the planet. In the closer edges of the ellipse, you are falling faster giving you the energy you need to shoot out to a further edge.
At any rate, I think I've explained this well enough, and it's explained further over at badastronomy.com (I'll link to it again because I have the nagging feeling you didn't read various bits regarding gravity at that site).
"On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question." ~ Charles Babbage (1791-1871)