# To space in 24 hours.

1. Aug 30, 2007

### perfectz

To space in 24 hours.........

If I were to hover in a helicopter for 24 hours by some means or the other, won't I be able to say Hi to space.
Because of the earth's revolution, and because I have overcome gravitational pull, wont I be able to enter space?

2. Aug 30, 2007

### mgb_phys

I assume you mean if you hover off the ground shouldn't the ground rotate under you and so you travel sideways.
Unfortunately not - the helicopter (and you and the air) is already being pushed sideways at 900mph by the rotating earth, when you hover you keep this componnet of the force.
Imagine you are on a train doing 100mph, if you jump in the air you do not suddenly go 100mph toward the back of the train.

Helicopters only work in air (and only relatively dense low altitude air) otherwise you could go stright up into space, it's only about 60miles above you! But because you still have the horizontal motion from the earth that you had on the ground you would still be rotating over the same point on earth.

3. Aug 30, 2007

### perfectz

4. Aug 30, 2007

### mgb_phys

Not sure what you mean.
I'm saying that stepping off the earth and waiting for the earht to go past you is exacly the same as launching a rocket. It takes the same energy and same time.

5. Aug 30, 2007

### perfectz

I know that It's an impossible thing to just hover and move from one place to another.
I just wanted a valid explanation.
If I jump really high from a moving train running with a velocity of 100 mph, WILL I NOT MOVE BACKWARD FOR AT LEAST SOME DISTANCE?

6. Aug 30, 2007

### mgb_phys

No - ignoring air resistance.

You have to think about all the forces involved, on a train you are being pushed along sideways at 100mph, if you jump up you are actually jumping up at a few mph and sideways at 100mph.

7. Aug 30, 2007

### Staff: Mentor

...and ignoring the coriolis force. But for simplicity, lets just say you can play ping pong on a train and you won't have to care that it is moving. That's the principle of relativity.

8. Aug 30, 2007

### Loren Booda

If you have a ball (representing Earth) spinning in a pool, you can observe at water level a rotating layer - comparatively as thick as the Earth's atmosphere - just outside the ball's surface. Think of the Earth as maintaining its spin due to tremendous initial momentum which it has transfered (in small part) by friction to its atmosphere over billions of years. Thus the atmosphere, largely, and anything within it move along relative to the Earth.

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