# Tunnel questions

1. Jul 5, 2008

### h.g.Whiz

suppose i constructed a highway from the atlantic coast to the gulf of mexico with its finish grade at sea level . suppose instead I dug a tunnel in a straight line. which one would be considered level . and if I dug the tunnel so that it resembled a skateboard ramp could the momentum built from the first half of the trip supply the energy for the second half or would it stop in the middle due to slight decrease in gravity . I can't think of the name game that you can find at most bars in which you slide a metal puck across a wood table thats covered in salt. but anyways I was thinking that if you could replicate similar conditions on a massive scale than it would be possible to travel or transport goods real far without fossil fueled engines

Last edited: Jul 5, 2008
2. Jul 5, 2008

### CompuChip

Gravitational force is conservative, so if your tunnel ends at the same height (or lower) than it started it will, in theory, not cost you any energy. Unfortunately in the "real" world, there are things like friction which always dissipate energy, whether you are moving up or down, so you would always have to add some energy to compensate for that.

3. Jul 5, 2008

### Danger

The game is 'Shuffleboard', and that's wax that gets sprinkled on it... essentially the same wax that they toss onto dance floors. It's very similar to curling, except that there's a lot less effort and almost no chance of freezing your *** off during a game.
In any event, you have to look at how much energy is expended to construct the system in the first place to determine whether or not it's efficient.

4. Jul 8, 2008

### faux

i'm confused on the straight line. is the straight line refers to a line in the curved earth's surface or a straight line in a plane of 2 points of consideration?

anyway, it's nearly impossible to achieve a system without energy dissipation in the real word. your idea of constructing such tunnel for that mode of transportation only so as to reduce fossil fuel consumption is just silly. construction projects are energy-guzzling endeavors from production of construction matertials to digging to erection to fabrication, maintenance etc.