Newton's 3rd Law and rockets


Lifting yourself up by your boot laces.

Rockets velocity is a lesser proportion of the exhaust gas velocity which is at the very best, 4,400 meters per second. Or 4.4 kilometers per second, or 15,840 kilometers per hour. So no rocket can exceed 15,000kph.

The speed of the orbiting space station is 27,600kph.

Question:

How on earth could the space shuttle ever speed up to the sped of the spacestation and how did they even get the spacestation to that speed in the first place?

The shuttle max theoretical speed is the same as the gas velocity, so its about 11,700 kph too slow to catch up and dock with the space station.

They say that in space, there is no other restrictions, like air resistance, or gravity, so after the rocket is already doing, say 5,000kph, they fire the engines again and from the gas’s frame of reference, the shuttle is not moving, so it’s the same effect as if the shuttle was just taking off again. So add another 5,000kph equaling 10,000. This is space rocket science at it's best.

This is an identical concept as the following example, which is the exact same “principal” but described in different words. See if you can spot the problem.

“I am an astronaut floating freely in the emptiness of space, and I am right beside my 1,000 ton space ship.I have with me a very light but stiff pole, made from carbon fiber, about 500 meters long.I use the pole to push myself away from the space ship, and my action is limited to muscle and arm movement, which has a velocity of 20 kilometers per hour. Great, now I’m moving away from the ship, at 20 kph with my pole.

In space, nothing will stop me, so Ill keep moving across space at 20kph practically forever. But before I get more than a meter away from the ship, I repeat the action. I use the pole again, giving myself another push.

Question: “How fast is my second push?”

Answer: I physically can only push at 20, so it’s another 20kph push. So the result of my second push will not add even the slightest bit of speed to my current velocity of 20kph.

Even if I continue to do this till Im 500meters away, and have no more pole left, I’m still only doing 20 kph.

But this is NOT what rocket scientists say will happen!

Here is what NASA says will happen.

First push causes me to move away from the ship at 20kph. Then I push again with a 20kph push, so I now will be going 40kph. And so on. After a while, I’m doing 200kph away from the ship and yet somehow I can still push against the ship with a 20kph motion. Does this sound physically possible to you?

This is NASA’s well known Law of Physics that states that “you can pull yourself up using you own boot laces.”

Why don’t you try it at home?

Get a kid’s push cart.

Push is as fast as you can run.

Now you and the cart are doing 20kph.

Now push it again, not using an arm motion, just from running at 20kph, and make the cart speed up to 40kph.

Or even 25, allowing for friction losses.

Ok even 22kph.

It can not be done.

Let’s say the cart is already doing 40, and you can run at 20. Try adding a push now.

What’s that you say? You can’t even catch up with the cart, and even if you did, there is no way to push at 20kph on an object that is moving faster.

Clearly Einstein and Rocket engineers never played with a kart.

Maybe try adding a few extra revs to a spinning electric fan. The fan blades are moving much faster than you fastest hand movement, so the end result is that you will get you fingers whacked, temporarily slowing the fan, not adding speed.

So, Rocket scientists, please explain how the shuttle can go faster than its engines can possibly drive it.

P.S. Recently I was banned from asking Questions on Physics Forums!. All I wanted was details on how I could run any sort of experiment to demonstrate the principal that a small speed push can add up to make a faster final speed. They said it is done in space. I asked was it ever demonstrated as a physics principal on earth? No.  Can it be done on Earth?  Yes, but we wont tell you how you might go about it. And because you are asking questions after being told that it works as stated by NASA, and you refuse to accept that, then you are banned from the Forum.

             

Mobirise
Author

Mark Ross
Derby
Tasmania  Australia

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