The conveyor belt thread.

[BlueBearBoots]

This reminded me of the question - if you throw a ball inside a carriage of a train travelling at 180mph how fast is the ball travelling and how far did it go?

 

[mad4city]

This reminded me of the question - if you throw a ball inside a carriage of a train travelling at 180mph how fast is the ball travelling and how far did it go?

Or...
If it takes two men a week to walk for a fortnight, how long would they need to sand King John's Castle down to a bungalow?

 

[Barcon]

Listen you dopey twats. The plane is "travelling at 180mph", despite being on a conveyor belt that is doing 180mph in the opposite direction. The speedometer on the plane must be reading 360mph or thereabouts. If the speedometer read 180mph the plane wouldn't be travelling. It doesn't say that the plane "was" travelling at 180mph and then someone turned on a conveyor belt causing the plane to stop travelling at 180mph.

 

[yerwot?]

Very disappointing, the myth-busters cocked up completely, the plane is Not stationary at all, it is clearly moving past the cones, which proves nothing whatsoever. Waste of space. They should stick to blowing things up.

 

[ColinBellsjockstrap]

This reminded me of the question - if you throw a ball inside a carriage of a train travelling at 180mph how fast is the ball travelling and how far did it go?

It depends whether the train stops at Cheadle Hulme or not.

 

[aguero93:20]

Just turn the fucking plane round and it'll take off.

 

[Gelsons Dad]

If a plane was travelling down a giant conveyor belt at 180mph, trying to take off, but the conveyor belt was travelling at 180 mph in the opposite direction, would it be able to?

You would still have the thrust of the jet engines at the back.

Some information about aeroplanes for those who don't know.

1) The instrument used to indicate speed in an aeroplane is called an Air Speed Indicator (ASI) it measures dynamic pressure and therefore the speed of the aeroplane through the air.

2) The wheels on and Aeroplane are not driven. They freewheel.

3) Thrust is a result of accelerating air through the engine. Mass times acceleration.

The original question states "If a plane was travelling down a giant conveyor belt at 180mph". To "travel down" infers the speed is relative to the conveyor belt surface. If this is the case then the speed of the aircraft relative to the ground on which the conveyor belt is placed would be zero and in still air the speed relative to the air would also be zero.

Now, as mentioned earlier. Speed on aeroplanes is measured relative to the air mass through which it is traveling. So if we read 180mph (we normally use nautical miles per hour called knots) on the ASI then the speed relative to the conveyor belt is 180 + 180 in still air ,360mph. If the air mass is moving (we call this wind :-) then the vector parallel to the aircrafts normal axis needs to be added or subtracted to calculate the speed of the aeroplane relative to the conveyor belt surface and/or the ground.

The original question throws a curve ball with the statement "You would still have the thrust of the jet engines at the back." This infers that the engines are running, which may lead us to believe they are propelling us through the air at 180mph. However, the engines could be at idle thrust providing just enough force to overcome the friction in the wheel axels. This would be required to hold our speed relative to the ground otherwise we would be "conveyed" by said belt.

So the question is worded in such a way that it is only possible to offer an answer if we infer some meaning to the ambiguous terms. Without that it is not possible to answer the question.

This has nothing to do with principles of flight. It's a comprehension and reasoning question. For which there is no definitive answer.

Now, if you say " If a plane was travelling down a giant conveyor belt at an indicated air speed of 180mph, trying to take off, but the conveyor belt was travelling at 180 mph in the opposite direction, would it be able to?

You would still have the thrust of the jet engines at the back."

The answer is yes so long as the tyres don't burst before it gets airborne.

or if you say "If a plane was travelling down a giant conveyor belt at a speed of 180mph relative to the surface of the belt, trying to take off, but the surface of the conveyor belt was travelling at 180 mph in the opposite direction and there was no wind relative to the entire system would it be able to?

You would still have some thrust of the jet engines at the back."

The answer is no.


Remember folks, Aeroplanes fly through the air.

 

[xgorton]

This reminded me of the question - if you throw a ball inside a carriage of a train travelling at 180mph how fast is the ball travelling and how far did it go?

That would take some shot.

 

[Gelsons Dad]

This reminded me of the question - if you throw a ball inside a carriage of a train travelling at 180mph how fast is the ball travelling and how far did it go?

That would take some shot.

If you throw a paper aeroplane inside a real aeroplane traveling a mach 1 how fast is your paper aeroplane traveling? ;-)

 

[york away to this!]

This reminded me of the question - if you throw a ball inside a carriage of a train travelling at 180mph how fast is the ball travelling and how far did it go?

That would take some shot.

If you throw a paper aeroplane inside a real aeroplane traveling a mach 1 how fast is your paper aeroplane traveling? ;-)

...depends which way you throw it - and whether someone left the doors open or not...