Lamppost cable. What are they for?

[Harry Bloomfield]

... and that's when I start getting confused about things like kinetic energy and momentum. They are both, mathematically, functions of velocity, yet velocity can be anything, depending on what it is measured relative to.

What confuses me - is the earth is spinning on its axis, the earth is also rotating around the sun. Which means that during the daylight hours, anyone stood on the earth will be accelerating relative to the sun, and during darkness, we are decelerating. Yet we feel nothing...

Rather like simply walking - each leg has to accelerate to double your speed, then suddenly come to a stop, relative to the ground..

 

[bernardgreen]

Yet we feel nothing...

You are just not sensitive enough,

https://en.wikipedia.org/wiki/Foucault_pendulum

Rather like simply walking

What part of a train can alternate continuously between travelling forwards at more than twice the speed of the train and then travelling backwards

 

[davelx]

!

 

[davelx]

 

[SUNRAY]

You are just not sensitive enough,

https://en.wikipedia.org/wiki/Foucault_pendulum



What part of a train can alternate continuously between travelling forwards at more than twice the speed of the train and then travelling backwards

Is this train specific

 

[bernardgreen]

Is this train specific

I cannot think of any other type of transport that has this property.

 

[SUNRAY]

I cannot think of any other type of transport that has this property.

I assume this is referring to a steam loco; In that case I can only think of a rotating mechanism but I don't think it's wheels, pistons or linkages.

Now intrigued.

 

[SUNRAY]

Maybe the exhaust relative to the speed of the train?

 

[SUNRAY]

Maybe the exhaust relative to the speed of the train?

Ohhhhh dear yes it will be ...

I won't spoil the fun yet. but I can think of 2 things.
PM sent.

 

[EFLImpudence]

The fireman's shovel.

 

[mikeyd]

I cannot think of any other type of transport that has this property.

Cable ferry.

 

[SUNRAY]

Cable ferry.

good one but I wonder if you understand why.

 

[SUNRAY]

The fireman's shovel.

Bloody fast worker!

 

[bernardgreen]

The fireman's shovel.

It is valid for electrical and deisel trains

 

[Harry Bloomfield]

You are just not sensitive enough,

https://en.wikipedia.org/wiki/Foucault_pendulum

Of course, now I remember having seen the pendulum in Paris, but a long time ago...

What part of a train can alternate continuously between travelling forwards at more than twice the speed of the train and then travelling backwards

Obvious one - the crank shafts on a steam engines wheels. Whilst they reverse, I don't think they travel backwards. To travel backwards, the crank pivot, where it attaches to the wheel, would have to be outside the diameter of the wheel.