 | Re: The Timeline, Bob, and You |
| Posted By: Steve Levinson | Date: 1/9/03 11:43 a.m. |
| In Response To: Re: The Timeline, Bob, and You (Finnigan)
: Are there G forces in space travel? What creates the gravity?
It's called Newton's second law - force equals mass times acceleration. Gravitational acceleration on earth is 32.2 feet/second/second (sorry about the use of English units). A gravitational force of 5 G's would then equate to more than 52 feet/sec/sec. I'ts a fairly simple matter to calculate the gravitational force for a particular acceleration, and it's easy to calcualte the acceleration needed to go a given distance in a given amount of time, assuming a constant acceleration. Just keep in mind that you need to decelerate as well as accelerate. so you would presumably accelerate for the first half of the trip and decelerate for the second half. You have to allow half the time for deceleration, as the G forces would be just as significant and no one can survive the infinite G forces associated with instantaneous deceleration (crash landing). Now there is a very interesting twist to all of this imposed by relativity. Although the observers on board the ship would see no end in sight to their acceleration, relativity comes into play as they approach the speed of light, slowing the passage of time for those on board relative to those back home.
Now all of this is in sharp contrast to the way we do things with space travel now, which is to basically accelerate a space vehicle very quickly and then let it coast for the duration of the voyage. A coasting space ship is not accelerating and, hence, has no associated gravity. The problem with the "hurl it into space" approach is that the speeds reached are not sufficient for a lengthy voyage - it would take hundreds of years just to travel the 4+ light years to our nearest neighbor. The big problem with constant acceleration, however, is the need for an equal opposing force to provide the acceleration (i.e. accelerating a space ship at a rate of 32.2 ft/sec/sec would require a constant force of 1G being applied to the space ship. The conventional way of doing this is by using a chemical reaction to accelrate a propellant out a rocket nozzel, letting the laws of conservation of momentum do the work. Even if you replace the chemical reaction by a 100% efficient process (complete matter-energy conversion in essence), you still need the propellant, which adds substantially to the overall mass of the ship which has to be accelerated in the frist place. Eventually you reach a point where the mass of propellant needed exceeds the total mass of the ship, including the propellant, a physical impossibility. Obviously, the Marathon found another way.
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| The Timeline, Bob, and You | Finnigan | 1/9/03 9:54 a.m. |
| Re: The Timeline, Bob, and You | Steve Levinson | 1/9/03 10:50 a.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/9/03 11:06 a.m. |
| Re: The Timeline, Bob, and You | Steve Levinson | 1/9/03 11:43 a.m. |
| Steve is wrong! OK, I lied - he's right. *NM* | poena.dare #CP# | 1/9/03 11:47 a.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/9/03 12:18 p.m. |
| Re: The Timeline, Bob, and You | poena.dare #CP# | 1/9/03 12:53 p.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/9/03 5:20 p.m. |
| Re: The Timeline, Bob, and You | poena.dare #CP# | 1/9/03 11:09 p.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/10/03 4:12 a.m. |
| Re: The Timeline, Bob, and You | Cybergeek | 1/10/03 7:55 p.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/11/03 7:05 p.m. |
| Re: The Timeline, Bob, and You | Cybergeek | 1/12/03 4:57 p.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/10/03 5:05 a.m. |
| Re: The Timeline, Bob, and You | poena.dare #CP# | 1/10/03 8:39 a.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/10/03 9:34 a.m. |
| Re: The Timeline, Bob, and You | poena.dare #CP# | 1/10/03 10:23 a.m. |
| Re: The Timeline, Bob, and You | SneakyPete | 1/16/03 5:49 p.m. |
| Just because i'm bored | Todd | 1/17/03 2:08 a.m. |
| Re: Just because i'm bored | Finnigan | 1/17/03 4:48 a.m. |
| Re: Just because i'm bored | Todd | 1/17/03 2:11 p.m. |
| Re: Just because i'm bored | Yossarian | 1/17/03 2:50 p.m. |
| Re: Just because i'm bored | Cybergeek | 1/17/03 3:04 p.m. |
| Re: Just because i'm bored | Cybergeek | 1/17/03 3:01 p.m. |
| Re: The Timeline, Bob, and You | DonPistola | 1/17/03 2:35 a.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/17/03 4:43 a.m. |
| Re: The Timeline, Bob, and You | Steve Levinson | 1/17/03 6:28 a.m. |
| Re: The Timeline, Bob, and You | poena.dare #CP# | 1/17/03 7:35 a.m. |
| Re: The Timeline, Bob, and You | Cojiro | 1/14/03 7:31 p.m. |
| Re: The Timeline, Bob, and You | poena.dare #CP# | 1/9/03 11:45 a.m. |
| Re: The Timeline, Bob, and You | Steve Levinson | 1/9/03 11:51 a.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/9/03 12:12 p.m. |
| Re: The Timeline, Bob, and You | Tru7h | 1/9/03 1:08 p.m. |
| Re: The Timeline, Bob, and You | Finnigan | 1/9/03 5:26 p.m. |
