savata71

You can also solve it via simple kinematics equations, without diff. eq.

Yes, of course – I saw it now. It is absolutely simple. And I am trying swim in deep waters…

Yes, if we use the law of conservation of energy. The potential energy in highest position is equal to kinetic energy in starting position. That way it can be solved without differential equation, indeed.

For #1 and #2 watch Lec 8 | 8.01 Physics I: Classical Mechanics, Fall 1999:

http://www.youtube.com/watch?v=uZGbtK2KBoY

and you will do them

#3 is much harder for understanding and solving - you have to pass through examples for how similar problems are solved.Because differential equations and integrations are involved.

ok, i understand

Ok, maybe the time is enough. Now I am checking it.

3. A vertical jump is performed and the only data made available to you is the flight time of the jumper which is 0.600 s. Calculate the jump height achieved. Report your answer to 2 decimal places.

The time here is not enough. Mass does't matter but you need a starting (initial) velocity to solve jump height.

I will try to write how it solves after consulting with my books.

The question about Newton’s laws and how they appear, especially when we talk about gyroscopes, is too hard for me. There are many things involved here. I just have to learn more.

For now I can give advice to those who will make computer simulations (like sterologist said before):

You saw how I made mistake in my suppositions and how simulating software confirm these wrong suppositions (unbelievable coincidence of mistakes).

So, be very careful when you make deductions based on computer simulations!

... the direction (axis) of that torque constantly changes.

But what changes it? - The reaction.

And what the Law says? - For every action there is an equal and opposite reaction.

If the reaction was opposite there would be no change in direction.

P.S. Ok I wrote it too fast... I am thinking now if the changeing of direcion of toorque means that the reaction is not opposite in every moment of time...

 

Angular velocity, or angular speed? There's a big difference.

Ok, I will try to understand the difference. In Bulgarian there is only one word for speed (or velocity) I think ...

Look carefully at the torque during precession. Is it constant?

Well, I can’t see the reason why torque not to be constant during precession. The magnitude of torque has influence on the speed of precession but this speed is constant.

Gyroscope just has strange reaction on torque. And this reaction is a criminal – it rudely breaks Newton’s laws:

Let’s imagine a stone with a gyroscope inside and we don’t know that. The gyroscope inside have constant angular velocity. And let’s imagine that we are in space without gravity.

1. Now there are no outside actions and noting happened – first Newton’s law is satisfied.

2. We decide to action on that stone with a constant torque (with two small jets for example) and, according to Newton’s second law, we expect this stone to start rotation with increasing angular velocity (angular acceleration). But stone respond us with rotation where angular velocity is constant. The second Newton’s law is broken.

3. According to Newton’s third law we expect equal and opposite reaction but what we find? Reaction in another direction. The third Newton’s law is broken.

It will be easier if the bullet have a form of boomerang.Then you can shoot round the corner:-)

Ok, I understand that I have to push something to get its reaction to push me, but by the same reason I can get a torque without being on a surface and there is no need to block the rotation to have a torque – if I rotate something it rotates me but there is a torque. So, this device could work if precession was a linear motion, but not angular.

I can’t answer to the question how is linear momentum being conserved here, because I don’t think that this device will work (for the present:-)), but the things are not always so clear.

What will you say about that:

While a torque acts on an object (gyroscope) the result is a CONSTANT angular speed motion (precession).

Instead of:

While a torque acts on an object the result is ACCELERATING angular speed motion.

The green arrows represent a vertical force if and only if there is an equal and opposite force to offset it. The reaction shows a torque or moment but if that point was fixed there would be a reactionary force there as well. If it is free to move at that point, that point will accelerate downward due to this equal and opposite force that is not shown. There will be no net lift. The thing might be able to jump, but it will never hover.

Yes, to my regret I think you are right …

Maybe something wrong happen with the simulating software when I transfer the models from Solid Edge to Parasolid and then to Visual Nastran.

I will try to make the model directly in Visual Nastran to see what will happen.

Merged post follows:

But the simulation program needs a force (or acceleration) in order to calculate the motion. How did you do that?

 

Precession is a constant angular speed motion in response to a torque. It's not a linear force.

Well, I thought that a tendency for precession which will appear in response to a motor torque (and which starting direction is UP) can oppose to gravity, but now I am very hesitate in my opinion.

There are known rules how to find in what direction the precession appears. I can't explain it in English now (I'm not sure that I can do this in Bulgarian too), but if you see this ocular demonstration

http://www.youtube.com/watch?v=8H98BgRzpOM&feature=related

you will agree with the smaller scheme in my previous post. The bigger scheme derives directly from the smaller.

Anyway, as to the OP, what is the equation you are using to find the "force" of precession?

If you ask me – I don’t know the equation. Here is my reason to believe. I hope you can read from picture. I just check this with the simulating program. If this reasoning is wrong, where is the mistake?

Agree, the real physical model will have the last world.

I am not absolutely sure if this works but I have to defend it until someone show proof that it does not.

I think to try it in real but it will be not soon as I am out of job. As soon as I start work I will spend some money for a little experiment.

For beginning I will try the same tests with other software. And if someone try it too it will be good to share what happen.

This is without solutions. You have to start simulation and wait.

I think this is enough.

Specially for stereologist who wants springs:

Here is a video I made with spring hanged model and some other files with solution include.

1. AntiGravity_Explorer_B.avi - http://dox.bg/files/dw?a=c027f491fb

2. Gyroscopic Flying Car - Gyroscopic Space Craft 4.WM3 - http://dox.bg/files/dw?a=b9c35b64ac

3. BG_Flying_Saucer_Loaded.WM3 - http://dox.bg/files/dw?a=eb50ca6d88

4. AntiGravity_Explorer_B.WM3 - http://dox.bg/files/dw?a=f175fcf80e

These addresses are temporary

AntiGravity_Explorer_A.zip

Here is the first. The others are too big and if I can't attach them with the results of solutions, I will attach them without results. You will have to start the simulations and to wait and see what happend.

IN Cosmos.zip

Well, maybe you are right about terminology – maybe I mix up “moment” and “torque”. But if you watch the first video you will understand what I mean. And I don’t think that there is a violation of the laws of motion. It can be taken as a specific appearance of the laws of motion (if it be proven by a real experiment, of course).

OK, I will post some files in next post.

Some simulations include gravity and some not. All I do is: I put motors in the model and start them. It can be seen when gravity is on and when it is off - there is an arrow that shows direction of gravity.

If precession is caused by a moment (gravity and its reaction) then what if WE induce the precession (by using a motor)? Will there be an induced force in the direction against gravity for instance? These simulations say yes...

Yes, but this software uses Newton's physics and it is not in violation with Newton's third law.

Why is there a net force pointing upwards? - In this video is explained why:

http://www.youtube.com/watch?v=q87-Lt8sCsY

It just flys off.

There is a precession induced by using a motor which induced force in the direction against gravity.But you have to see the videos to understand me.

I am sure that the following will be interesting to be seen.

http://www.youtube.com/user/savata71

These are computer simulations ( I have made with MSC Visual Nastran 4D) of a gyroscopic device that overcomes gravity. And these simulations say it works.

So, what you think?