It's been a while - and we have new blood...

[Albannach]

if you're travelling on a train doing 90mph and throw a ball towards the front of the train, what speed is the ball travelling at?

v=tv+bv

[GBV8]

Here's one. What happens if you T-Bone your ship into another whilst drunk?
























Oh dear!

[Wolfracer]

v=tv+bv

Sure about that?
The air in the carriage is most probably stationary. The ball is moving through the air at bv.
The train is viewed as a closed system.

[Wolfracer]

Here's one. What happens if you T-Bone your ship into another whilst drunk?

Quietly slip off to your quarters and look surprised when they come knockin'...

[Albannach]

Sure about that?

Yes.

[Wolfracer]

Yes.

Oh. Well you're wrong.

[Albannach]

Oh. Well you're wrong.

Ah well.

[Albannach]

Speed and velocity are different. Speed is linear, velocity isn't.

It's possible for something to have a positive speed, but zero velocity. Take a ball thrown at a wall from a fixed point, if one throws the ball at a wall and catches it when it bounces back (provided it's caught at the exact point of release), the ball has attained speed, but no velocity; as it's now back at its starting point. The motion of the ball has not resulted in a change of position, therefore the ball's velocity is zero.

A ball thrown on a moving train cannot return to the point of release, therefore it has a positive velocity. Assuming the ball is cought at exactly the same point within the train's carriage, it has the same velocity as the train, so my equation above is correct.

v=tv+bv
v=tv+0
v=tv

Edit: Simplified as well, because the ball obviously can't return to the exact point of release...

[Wolfracer]

See post 81
Inside the train, tv is irrelevant.
outside the train it is.
Is it not?

[Maverick]

If a tree falls in the woods, and there is no one to hear it. Does it make a sound?

[Sancho]

If a tree falls in the woods, and there is no one to hear it. Does it make a sound?

Only if there's a dead cat in a box.

[Mork]

wheels no wheels still wont take off,
planes engines push plane forward to say 50mph where enough air flow is achieved then lift is achieved.
Pane > 50mph
Belt < 50mph
= no movementr in either direction, without movement there is no air flow over the wings so no lift

I'm sorry to say you have missed a fundamental point of the riddle.
(or you are just playing the wind-up game)
The whole point of the riddle is that the airplane is moved by the propellers not the wheels.

For example.
A piece of glass is suspended over a conveyor 3 foot in front of a car.
The conveyor belt moves backwards at the same speed as the car moves forwards. would the car ever hit the glass.
The answer is of course, NO.
Everyone knows that cars and conveyors cancel each other out.

But the reason a plane is used in the riddle is because the planes movement is not determined by the wheels.

Consider this
A plane is flying above a conveyor a mere 2 foot above the ground.
The plane is flying at 50mph, the conveyor is moving the other way at 50mph.
If the plane lowers it's wheels then the wheels will spin at 100mph, but the plane and conveyor will continue to move at 50mph.
(bearings resistance and aerodynamics accepted)

The conveyor has no impact on the movement of the plane.
It just has an impact on the rotation of the wheels.

[BUSHWHACKER]

See post #60.

[Predictable Bob]

I'm sorry to say you have missed a fundamental point of the riddle.
(or you are just playing the wind-up game)

I don't normally post spoilers but the people this thread is targeted at won't realise ...

This thread is just the latest incarnation of a windup that's been around for ages - the participants that are in the know change their position in a random fashion in the hope that a ruck will kick off with one of the more volatile members

(Unless I've totally missed the point and the forum really DOES have that many complete feckwits in it !)

[TonyN]