Too good to be true?

[Advocate]

This thread appears to have attained perpetual postings...

[Spacecadet]

Again, I refer you to the Gravity Train first examined by Hook and described to Newton. I don't know what Newton thought about it. Personally I think a slippery flat surface (or even magnetically levitated surface, etc) would be equally as good in practise, but that's not the point.

What you fail to grasp is that the gravity train will continue to move backwards and forwards between the 2 points untill something stops it.
The best place to stop it will be when its velocity reaches zero - ie then you can expend the least amount of energy stopping it. But you must still DO something to stop it moving

[realityhack]

ENOUGH

WHS

[DogTown]

So to summarise:

A gravy train would be the most eco-friendly method of transport?

[TimberWolf]

What you fail to grasp is that the gravity train will continue to move backwards and forwards between the 2 points untill something stops it.
The best place to stop it will be when its velocity reaches zero - ie then you can expend the least amount of energy stopping it. But you must still DO something to stop it moving

Ignoring losses (which we are trying to minimise) it would stop at exactly the height it fell from. Just like a planet orbiting the Sun. In reality, because of friction, it would top short and would have to be carried up the rest of the way. In view of the fact that it takes say 0.5 tonnes of fuel to take a passenger on a long haul flight in a 747, I would suggest this would still be a more efficient mode of transport than flying. Digging the hole and turning Earth into Swiss Cheese however might bankrupt Earth. Can't have everything. It's just one idea.

[Gonzo]

Fantastic. Handbagging over physics is so much more satisfactory than the handbagging over trivial things that we normally get on here.

Keep up the good work chaps.

[BrilloPad]

Today I went to the greencentre. Going on rollercoaster. We walked up hill to start. Fenincular(sp?) ride downhill (which lifts up rollercoster). We walk up to rollercoaster. Goes down by gravity.

Why cant they just burn more coal.

[Diver]

Just read this thread


Come back Sasguru, all is forgiven

[scooterscot]

Is the glass half empty or is it half full?

I always answer 'the glass is as twice as big as it needs to be'

often the retort is 'blo£$dy engineers'

[Numpty]

What if I drop a helium filled balloon?

Then the air above it falls around the balloon and settles under it. The balloon's 'desire' to fall is weaker. More and more air falls around and settles under it, pushing the balloon up in the process.

Helium balloons don't float up, they are suspended on fallen air.