Speed of flight
Imagine (Or build) a hovercraft fan fastened to the front of a car facing foward, and a small contraption that will drop table tennis balls into the airstream from the fan. A sensor also attatched to the car measures the speed of the pingpong balls in the airstream when the fan is running to be 40 miles per hour.
Now start the car and drive forwards at 40 miles per hour( against the direction of the fan).
What speed does the sensor measure the balls to be travelling?
What speed does a sensor fastened to the ground measure the speed of the balls to be?
Now start the car and drive forwards at 40 miles per hour( against the direction of the fan).
What speed does the sensor measure the balls to be travelling?
What speed does a sensor fastened to the ground measure the speed of the balls to be?
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I was hoping this might be analogous to the question about how fast the light from a car's headlight is travelling when the car is moving, hence the title.
I thought it might be a measurable experiment to show that simple addition isn't the answer.
Perhaps I could use a leaf blower instead of the open fan and measure the airspeed at the nozzle?
Would this still have different speeds depending on the distance from the nozzle?
I thought it might be a measurable experiment to show that simple addition isn't the answer.
Perhaps I could use a leaf blower instead of the open fan and measure the airspeed at the nozzle?
Would this still have different speeds depending on the distance from the nozzle?
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Ozo, you lost me with Galilean, is that an easy reference or something I would need to spend time on?
Thanks for the replies, I thought it might lead to a way of explaining light's speed limit, but apparantly it won't.
Bill, not homework, just sonething I wondered while I was cleaning my teeth the other day (onr of those times you can let your mind wander).
Thanks for the replies, I thought it might lead to a way of explaining light's speed limit, but apparantly it won't.
Bill, not homework, just sonething I wondered while I was cleaning my teeth the other day (onr of those times you can let your mind wander).
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Aburr, I'm not trying to disprove anything, just trying to find an easier way to understand it.
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Thanks for comments. My sttempt at an analogy has obviously failed.
I was thinking that the surrounding air would stall the forward motion if the fan, which as was stated is capable of accelerating a ping pong ball to 40 miles per hour in still air, so if driven forward would still only accelerate the balls to 40 mph relative to the surrounding air, not to the fan.
I watched an air show several years ago with a plane called an Optica. It was a windy day, about 30mph, the plane had a stall speed of about 20 mph and the pilot was able to fly the prop plane backwards in front of us with the prop driving him into the wind. It was very impressive.
I thought light may behave in a similar way, unable to go any faster no matter what was the relative movement of its source.
I was thinking that the surrounding air would stall the forward motion if the fan, which as was stated is capable of accelerating a ping pong ball to 40 miles per hour in still air, so if driven forward would still only accelerate the balls to 40 mph relative to the surrounding air, not to the fan.
I watched an air show several years ago with a plane called an Optica. It was a windy day, about 30mph, the plane had a stall speed of about 20 mph and the pilot was able to fly the prop plane backwards in front of us with the prop driving him into the wind. It was very impressive.
I thought light may behave in a similar way, unable to go any faster no matter what was the relative movement of its source.
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*of the fan
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You need to factor in the headwind, that's the whole point. Headwind created by moving the car through air. The speed generated by the fan when the car is at rest is given. I don't think the fan will be able ti propel the balls any faster with respect to a stationary observer.
I know this is not the same mathematics as light, but it is an often asked question.'if I ride my bike then isn't the light coming out of the lamp going faster?'.
I was/am looking for a way to demonstrate that adding a bit of movement to the source does not necessarily increase tbe speed of whatever is being projected.
(unlike a javelin thrown from a moving platform).
I know this is not the same mathematics as light, but it is an often asked question.'if I ride my bike then isn't the light coming out of the lamp going faster?'.
I was/am looking for a way to demonstrate that adding a bit of movement to the source does not necessarily increase tbe speed of whatever is being projected.
(unlike a javelin thrown from a moving platform).
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The fan experiment is designed to factor in wind resistance, the javelin description was not. If you can throw a javelin 50 yards from a standing position, you will be able to throw it further if you are moving, that's why they run as they throw them.
The ping pong balls are dependant only on airspeed so moving against the flow if air will have a noticeable affect.
The ping pong balls are dependant only on airspeed so moving against the flow if air will have a noticeable affect.
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bugger!! You all just gave my super computer a nervous breakdown. : |
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>> The ball is not mounted but the fan is.
picky picky picky. ; )
>> ...it wouldn't be invariant in the other direction.
whoops. the computer just crashed, again. : (
picky picky picky. ; )
>> ...it wouldn't be invariant in the other direction.
whoops. the computer just crashed, again. : (
ASKER
I think it was aburr that suggested using guns and cats and shooting rearwsrds. Not at all what I am describing.
There is no gun, just a moving airstream generated by a fan which itself is being driven forwards.
Stick it in a wind tunnel if you like.
The big fan driving the wind tunnel is much more powerful( moves more air) than tbe small hovercraft fan. If both are spinning at a rate that would drive still air at 40mph and both running at once, the draft from the little fan will not push air against the main fan at 40 mph as this would be a difference if 80 which the small fan is not capable of.
Maybe the existance of aether would help my anlogy.
I am only trying to answer the moving light source question, but trying to find a simpler way than using higher mathematics, dimensions or transforms.
So far without a lot of reading the answer is 'it doesn't', which is never a good answer when someone asks 'why?'.
There is no gun, just a moving airstream generated by a fan which itself is being driven forwards.
Stick it in a wind tunnel if you like.
The big fan driving the wind tunnel is much more powerful( moves more air) than tbe small hovercraft fan. If both are spinning at a rate that would drive still air at 40mph and both running at once, the draft from the little fan will not push air against the main fan at 40 mph as this would be a difference if 80 which the small fan is not capable of.
Maybe the existance of aether would help my anlogy.
I am only trying to answer the moving light source question, but trying to find a simpler way than using higher mathematics, dimensions or transforms.
So far without a lot of reading the answer is 'it doesn't', which is never a good answer when someone asks 'why?'.
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The why is almost the first question anyone asks when told nothing can travel faster than light and they say 'Why' doesn't the light from my bicycle lamp go faster when I am moving.
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The more of this thread I read the less I understand about the question(s) it supposedly poses.
Light, schmight!
Whose balls even get close to c ?
I'm sticking with my original post that answered the original 2 questions.
:-Þ
Light, schmight!
Whose balls even get close to c ?
I'm sticking with my original post that answered the original 2 questions.
:-Þ
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Why?
Because.
Get over it.
Get over it.
How long do I have to implement that?
Until 2014
kewl... 366 days should be enough.
ASKER
This didn't go the way I'd hoped at all. Thanks to those who attempted to understand the question. I was hoping to keep the mysteries of speed of light out of it and keep it to ping pong balls being blown by a fan, but it seems even that becomes confusing.
I just clicked most of the boxes hoping that everyone would get some in varying quantities.
I just clicked most of the boxes hoping that everyone would get some in varying quantities.
Thank you much. : )
Thank you Robin
Any analogy can be misleading if you try to interpret it too literally,
and Minkowski geometry can seem unintuitive if you're not used to it,
but this analogy for the cosmic speed limit may be both reasonably easy to understand and not too terribly misleading:
http://youtu.be/IM630Z8lho8
and Minkowski geometry can seem unintuitive if you're not used to it,
but this analogy for the cosmic speed limit may be both reasonably easy to understand and not too terribly misleading:
http://youtu.be/IM630Z8lho8
I don't know about the rest of you but MY velocities add up exactly.
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