as for the question 'the next one is can u travel faster than wind in direction of wind using nothing but the wind?' my initial thinking was that it might be possible to move faster than the wind but probably not in the exact direction of the wind. you'd really need to ask a sailor.
Yes certainly you can travel faster than the wind just not in the direction of the wind, sailors do it all the time. That's because you can mount the sail at an angle where it will keep adding (to a point) power from the wind even though the boat is going faster than the wind.
An object in motion stays in motion, or something like that unless another force is applied to it.
When you jump inside the plane you carry on at the planes speed because there is no force to slow you down (at least not noticably).
If you jumped out of the plane, air resistance would rapidly slow you down but you don't have that in the plane because you are inside. It's the plane that's cutting through the air, not you.
You need to think of acceleration and velocity as vectors, put simply this means they have direction as well as speed.
The space station is under the influence of the Earth's gravity and as it has to it accelerates towards the centre of the earth otherwise it would break Newton's laws. However the space station also has a velocity at a tangent (sideways) to the Earth. So whilst the station moves towards the Earth it also moves sideways, add the two up and continue in time then what happens is that the space station moves around the Earth in orbit.
EDIT: It might help you to understand if you consider what would happen if gravity suddenly stopped, the space station would go flying off into space at right angles. This is because the acceleration towards the Earth has stopped.
The plane is not going fast enough to be in orbit, if you turned off the engines the plane would plummet towards the ground (ignore the gliding caused by the wings).
Another question aboit orbits that's always confused me a bit.
As I understand it for something to be in orbit it needs to be moving at a certain speed. Whether its a planet orbiting the sun or a satellite orbiting the Earth the same rules apply.
If its moving too slowly it will fall in towards the Earth/Sun and eventually crash into the surface.
If its moving too fast it will fly off into space and escape the gravity of the Earth/Sun.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
My question is why do so many things (planets, moons etc) just happen to be moving at the exact speed required for them to be in orbit.
I'm guessing that I'm probably asking the question the wrong way round and the answer is something along the lines of things move at that speed because they are in orbit, rather than things go into orbit becasue they are at the right speed, but can anyone explain it properly.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
Yes
This is also the reason why all man-made satellites in geo-stationary orbits, that is to say that they appear to be permanently above the same point on Earth's surface, have to all be at the exact same height and it's getting rather crowded up there now.
As I understand it for something to be in orbit it needs to be moving at a certain speed. Whether its a planet orbiting the sun or a satellite orbiting the Earth the same rules apply.
If its moving too slowly it will fall in towards the Earth/Sun and eventually crash into the surface.
If its moving too fast it will fly off into space and escape the gravity of the Earth/Sun.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
It's self correcting. If the satellite is moving to fast it will move away from the Earth, this will cause it to gain potential energy (like when you lift a rock you can then drop it on your toe) at the cost of kinetic energy (speed) until it is in the right orbit. If it is moving too slow it will move closer to the Earth losing potential energy but gaining kinetic energy until it is just right.
Of course it can also just crash into the Earth or leave orbit altogether if the speed is out by too much.
As I understand it for something to be in orbit it needs to be moving at a certain speed. Whether its a planet orbiting the sun or a satellite orbiting the Earth the same rules apply.
If its moving too slowly it will fall in towards the Earth/Sun and eventually crash into the surface.
If its moving too fast it will fly off into space and escape the gravity of the Earth/Sun.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
So far so good...
My question is why do so many things (planets, moons etc) just happen to be moving at the exact speed required for them to be in orbit.
I'm guessing that I'm probably asking the question the wrong way round and the answer is something along the lines of things move at that speed because they are in orbit, rather than things go into orbit becasue they are at the right speed, but can anyone explain it properly.
I love it when people answer their own questions!
The other point to bear in mind is that the speed determines the distance at which you can orbit - a higher altitude lets you orbit at a slower speed. So an object captured by gravity will "find" the orbit appropriate to its speed. For example, as the Moon slows due to tidal drag, it is moving away from the Earth (at about 3cm per year, IIRC).
Yes certainly you can travel faster than the wind just not in the direction of the wind, sailors do it all the time. That's because you can mount the sail at an angle where it will keep adding (to a point) power from the wind even though the boat is going faster than the wind.
If that's the case, then there's nothing theoretically stopping a vehicle travelling indefinitely faster than the wind in the direction of the wind.
1) Get upto speed (> wind)
2) Switch the vehicle to "frictionless mode" (e.g. pull in sails etc)
3) Turn in whatever direction you want i.e. in the direction of the wind.
4) Continue travelling indefinitely at constant speed.
No physical laws such as conservation of energy or momentum would be broken.
This is also the reason why all man-made satellites in geo-stationary orbits, that is to say that they appear to be permanently above the same point on Earth's surface, have to all be at the exact same height and it's getting rather crowded up there now.
The main point with geostationary orbits is that satellites close to Earth have to orbit faster than those further out and geostationary is just at the point where orbits shorter than 24 hours turn into orbits longer than 24 hours. (I'm sure you know that I'm just clarifying it for John).
It's self correcting. If the satellite is moving to fast it will move away from the Earth, this will cause it to gain potential energy (like when you lift a rock you can then drop it on your toe) at the cost of kinetic energy (speed) until it is in the right orbit. If it is moving too slow it will move closer to the Earth losing potential energy but gaining kinetic energy until it is just right.
Of course it can also just crash into the Earth or leave orbit altogether if the speed is out by too much.
OK, thanks, that makes sense.
I guess its a good job its self correcting like that else we wouldn't be here to ask the question in the first place!
The main point with geostationary orbits is that satellites close to Earth have to orbit faster than those further out and geostationary is just at the point where orbits shorter than 24 hours turn into orbits longer than 24 hours. (I'm sure you know that I'm just clarifying it for John).
If I can just pick some nits, you are describing geosynchronous orbits. A geostationary orbit also requires that the satellites be above the equator (which is where the crowding comes in).
Another question aboit orbits that's always confused me a bit.
As I understand it for something to be in orbit it needs to be moving at a certain speed. Whether its a planet orbiting the sun or a satellite orbiting the Earth the same rules apply.
If its moving too slowly it will fall in towards the Earth/Sun and eventually crash into the surface.
If its moving too fast it will fly off into space and escape the gravity of the Earth/Sun.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
My question is why do so many things (planets, moons etc) just happen to be moving at the exact speed required for them to be in orbit.
There's no exact speed for something to be in orbit, but a range (for any particular direction+distance). All orbits are elliptical, and only in the special case are they circular - this is when the speed and distance remain constant. So if there's a satellite in orbit and you increase it's speed a bit, it will stay in orbit, but will follow a different path. In the general case orbits are elliptical and the speed of a satellite increases as it moves closer to the planet, and decreases as it moves further away.
Planets have orbits which are usually close to circular, but not exact. Pluto has a more eccentric orbit so sometimes is closer to the sun than Neptune and sometimes further away. Comets of course tend to have very elliptical orbits, so much so that a small change can occasionally cause one to hit the sum.
Yes certainly you can travel faster than the wind just not in the direction of the wind, sailors do it all the time. That's because you can mount the sail at an angle where it will keep adding (to a point) power from the wind even though the boat is going faster than the wind.
Now that you've quoted me I noticed an error in my post. I shouldn't have said "keep adding power" but should have said "keep adding energy" or "keep applying power".
If that's the case, then there's nothing theoretically stopping a vehicle travelling indefinitely faster than the wind in the direction of the wind.
1) Get upto speed (> wind)
2) Switch the vehicle to "frictionless mode" (e.g. pull in sails etc)
3) Turn in whatever direction you want i.e. in the direction of the wind.
4) Continue travelling indefinitely at constant speed.
No physical laws such as conservation of energy or momentum would be broken.
I wonder if there isn't some clever turbine blade design where parts of the blade are moving at such an angle that even when the body of the vehicle is going faster than the wind that part of the blade is still going slower and can take energy from it. I'm way out of my depth on this one as I'm not a mechanical/aeronautical engineer or similar but it doesn't sound too outlandish.
Another question aboit orbits that's always confused me a bit.
As I understand it for something to be in orbit it needs to be moving at a certain speed. Whether its a planet orbiting the sun or a satellite orbiting the Earth the same rules apply.
If its moving too slowly it will fall in towards the Earth/Sun and eventually crash into the surface.
If its moving too fast it will fly off into space and escape the gravity of the Earth/Sun.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
My question is why do so many things (planets, moons etc) just happen to be moving at the exact speed required for them to be in orbit.
I'm guessing that I'm probably asking the question the wrong way round and the answer is something along the lines of things move at that speed because they are in orbit, rather than things go into orbit becasue they are at the right speed, but can anyone explain it properly.
Hope that makes sense!
if say the moon were moving at the wrong speed it wouldn't be the moon it would just be some other random asteroid that you'd never heard of as it would have hit the earth a long time a go or flown off.
as has been said it can be self correcting in a sense as something falls it's gravitational potential energy is converted in to kinetic energy speed and vice versa.
it's quite complicated to work out what can and can't be captured into a stable orbit. but i will try.
all natural orbits are elliptical, not circular, even the moon and earth. if the earth, say, were a point mass rather than the size of a planet....
...then anything vaguely near it would be drawn towards and accelerate as it approached. if it had some, any velocity to start with that was in any direction other than straight at the earth it would build up huge speed, but that element of the original speed would still be there and cause it to miss the point earth.
it would loop around very close to the earth and be flung off at high speed and start escaping again, only to be drawn back eventually and the process to continue. it would form a very narrow elliptical orbit.
obviously the earth is not a point but the size of a planet so if the initial tangential velocity is too slow it will hit the earth.
If that's the case, then there's nothing theoretically stopping a vehicle travelling indefinitely faster than the wind in the direction of the wind.
1) Get upto speed (> wind)
2) Switch the vehicle to "frictionless mode" (e.g. pull in sails etc)
3) Turn in whatever direction you want i.e. in the direction of the wind.
4) Continue travelling indefinitely at constant speed.
No physical laws such as conservation of energy or momentum would be broken.
i think the question is asking if you can be powered by the wind in the direction of the wind faster than the speed of that wind.
your answer is not being powered by the wind in the direction of the wind. it's the same as charging up a battery with a wind turbine for half an hour and then letting it go.
i guess a simple test is that in order to be a solution it has to be sustainable.
if say the moon were moving at the wrong speed it wouldn't be the moon it would just be some other random asteroid that you'd never heard of as it would have hit the earth a long time a go or flown off.
as has been said it can be self correcting in a sense as something falls it's gravitational potential energy is converted in to kinetic energy speed and vice versa.
it's quite complicated to work out what can and can't be captured into a stable orbit. but i will try.
all natural orbits are elliptical, not circular, even the moon and earth. if the earth, say, were a point mass rather than the size of a planet....
...then anything vaguely near it would be drawn towards and accelerate as it approached. if it had some, any velocity to start with that was in any direction other than straight at the earth it would build up huge speed, but that element of the original speed would still be there and cause it to miss the point earth.
it would loop around very close to the earth and be flung off at high speed and start escaping again, only to be drawn back eventually and the process to continue. it would form a very narrow elliptical orbit.
obviously the earth is not a point but the size of a planet so if the initial tangential velocity is too slow it will hit the earth.
Comments
Yes certainly you can travel faster than the wind just not in the direction of the wind, sailors do it all the time. That's because you can mount the sail at an angle where it will keep adding (to a point) power from the wind even though the boat is going faster than the wind.
When you jump inside the plane you carry on at the planes speed because there is no force to slow you down (at least not noticably).
If you jumped out of the plane, air resistance would rapidly slow you down but you don't have that in the plane because you are inside. It's the plane that's cutting through the air, not you.
There, simple
Another question aboit orbits that's always confused me a bit.
As I understand it for something to be in orbit it needs to be moving at a certain speed. Whether its a planet orbiting the sun or a satellite orbiting the Earth the same rules apply.
If its moving too slowly it will fall in towards the Earth/Sun and eventually crash into the surface.
If its moving too fast it will fly off into space and escape the gravity of the Earth/Sun.
So for a body orbiting at a specific distance it needs to be moving at exactrly the right speed. Correct?
My question is why do so many things (planets, moons etc) just happen to be moving at the exact speed required for them to be in orbit.
I'm guessing that I'm probably asking the question the wrong way round and the answer is something along the lines of things move at that speed because they are in orbit, rather than things go into orbit becasue they are at the right speed, but can anyone explain it properly.
Hope that makes sense!
This is also the reason why all man-made satellites in geo-stationary orbits, that is to say that they appear to be permanently above the same point on Earth's surface, have to all be at the exact same height and it's getting rather crowded up there now.
It's self correcting. If the satellite is moving to fast it will move away from the Earth, this will cause it to gain potential energy (like when you lift a rock you can then drop it on your toe) at the cost of kinetic energy (speed) until it is in the right orbit. If it is moving too slow it will move closer to the Earth losing potential energy but gaining kinetic energy until it is just right.
Of course it can also just crash into the Earth or leave orbit altogether if the speed is out by too much.
I love it when people answer their own questions!
The other point to bear in mind is that the speed determines the distance at which you can orbit - a higher altitude lets you orbit at a slower speed. So an object captured by gravity will "find" the orbit appropriate to its speed. For example, as the Moon slows due to tidal drag, it is moving away from the Earth (at about 3cm per year, IIRC).
1) Get upto speed (> wind)
2) Switch the vehicle to "frictionless mode" (e.g. pull in sails etc)
3) Turn in whatever direction you want i.e. in the direction of the wind.
4) Continue travelling indefinitely at constant speed.
No physical laws such as conservation of energy or momentum would be broken.
The main point with geostationary orbits is that satellites close to Earth have to orbit faster than those further out and geostationary is just at the point where orbits shorter than 24 hours turn into orbits longer than 24 hours. (I'm sure you know that I'm just clarifying it for John).
OK, thanks, that makes sense.
I guess its a good job its self correcting like that else we wouldn't be here to ask the question in the first place!
I'm sure James Burke could explain better.
Planets have orbits which are usually close to circular, but not exact. Pluto has a more eccentric orbit so sometimes is closer to the sun than Neptune and sometimes further away. Comets of course tend to have very elliptical orbits, so much so that a small change can occasionally cause one to hit the sum.
Now that you've quoted me I noticed an error in my post. I shouldn't have said "keep adding power" but should have said "keep adding energy" or "keep applying power".
I wonder if there isn't some clever turbine blade design where parts of the blade are moving at such an angle that even when the body of the vehicle is going faster than the wind that part of the blade is still going slower and can take energy from it. I'm way out of my depth on this one as I'm not a mechanical/aeronautical engineer or similar but it doesn't sound too outlandish.
as has been said it can be self correcting in a sense as something falls it's gravitational potential energy is converted in to kinetic energy speed and vice versa.
it's quite complicated to work out what can and can't be captured into a stable orbit. but i will try.
all natural orbits are elliptical, not circular, even the moon and earth. if the earth, say, were a point mass rather than the size of a planet....
...then anything vaguely near it would be drawn towards and accelerate as it approached. if it had some, any velocity to start with that was in any direction other than straight at the earth it would build up huge speed, but that element of the original speed would still be there and cause it to miss the point earth.
it would loop around very close to the earth and be flung off at high speed and start escaping again, only to be drawn back eventually and the process to continue. it would form a very narrow elliptical orbit.
obviously the earth is not a point but the size of a planet so if the initial tangential velocity is too slow it will hit the earth.
your answer is not being powered by the wind in the direction of the wind. it's the same as charging up a battery with a wind turbine for half an hour and then letting it go.
i guess a simple test is that in order to be a solution it has to be sustainable.
Good explanation!