Re: gravitational force -airplane motion and earths rotation
From: Androcles (androc1es_at_nospamblueyonder.co.uk)
Date: 08/20/04
- Next message: Richard Saam: "wave length to vibrational dimension ratio"
- Previous message: No Way: "Re: gravitational force -airplane motion and earths rotation"
- Maybe in reply to: No Way: "Re: gravitational force -airplane motion and earths rotation"
- Next in thread: Nick Maclaren: "Re: gravitational force -airplane motion and earths rotation"
- Reply: Nick Maclaren: "Re: gravitational force -airplane motion and earths rotation"
- Messages sorted by: [ date ] [ thread ]
Date: 20 Aug 2004 09:30:57 -0400
"surendra" <efuzzyone@netscape.net> wrote in message
news:cg3248$5cd$1@news.asu.edu...
|
| Hi,
| I was having a hot debate with my friend in which we were arguing about
| airplane motion.
| What my friend was saying was that when the airplanes they fly, because
| of the earth's rotation from west to east, it takes them(planes) shorter
| time to go from east to west compared to from west to east.
| In other words, a plane flying from London to New York will take less
| time compared to a plane flying from New York to London. I was
| contending that they will take equal time.
|
| Are there any experts around who can answer who is correct and with
reason?
|
http://www.virgin-atlantic.com/bookflightsandmore/bookflights/searchFlight.do
London (LHR)
20 AUG 14:00 New York (JFK)
20 AUG 16:40 =
2:40 + 5 hours (EST - GMT =5:00) = 7:40 outbound
New York (EWR)
21 AUG 08:20 London (LHR)
21 AUG 20:00
= 11:40 - 5 (GMT - EST = -5:00) = 6:40 inbound.
The reason for the 1:00 hour difference is the high wind blowing the plane
along (or opposing it), and nothing else. If we ignore the jet stream, the
times will be the same. A real flight will be subject to various delays, of
course, and you may get in early or late.
| I was arguing with them that when the earth rotates the plane also
| rotates with the earth and they have almost similar speed of rotation.
Well, all motion is relative. New York is about 40 degrees North of the
equator and London 52 degrees latitiude, So we'll take 45 as the mean.
The equator, relative to the Sun, is about 25,000 miles in diameter and
completes onw revolution in one day, so it os moving at 25,000/24 miles per
hour, or a bit over 1000 mph. The pole has no distance to go, and at 45
degrees we use the cosine, so cos(45) = 0.707, multiply that by 1000, so New
York and London are moving at about 700 mph relative to the Sun.
Using round figures, they are about 2800 miles apart, the plane takes 7 hour
s, so it moves at 400 mph ground speed (the air is thinner at 30,000 ft, so
the planes 'speedometer' (actually called the 'air speed indicator') only
records 250 mph air speed. From East to West, then, the plane moves at 700 +
400 = 1100 mph relative to the sun, travels 2800 miles at 400 mph = 7 hours.
Coming back, West to East, it travels 700-400 = 300 mph relative to the sun,
but still takes 2800 miles at 400 mph (relative to the ground) = 7 hours to
return. So you book a day flight during the outbound trip, you leave at
2:00 in the afternoon and arrive in New York at 4:40 the same afternoon,
local time, and coming back you only travel at 300 mph, relative to the sun,
taking off at 8:20 am and arriving at 10:00 in the evening. Jet lag is a
killer, you gain a day going and lose a day coming back.
| I was arguing that the revolution of moon around the earth(or earth
| around the sun, etc., ) is like rotating with a hammer-throw (an olympic
| sport in which there is a heavy ball tied at the end of a chain, which
| the atheletes has to throw the furthest). When we are still the
| hammer-throw is close to us and still. But when we start rotating the
| hammer throw revolves around us, and it starts going farther away from
| our body. It is the speed of our rotation which decides how far it is
| away from our body. So, in case of heavenly bodies(earth and moon) it is
| the gravitational force. I was further contending that if the earth
| slowly stops rotating, then the moon will collapse into the earth.
No, sorry, you are way off with that one. There is no chain tying the moon
the earth. The moon takes 28 days to orbit the earth, and the Earth rotates
on its own axis in one day. The nearest you have to your idea is a
communications satellite that people point dish antennae at to get TV
pictures and send phone calls through, and they are at 22,300 miles high.
They take 24 hours to go around the earth once, and because the earth turns
once every 24 hours, the dishes always point to the satellite. If the earth
slowed down, we would have to move the satellites further away, but that
would be deliberate on our part. If the earth stopped dead, with the Sun
overhead at one place, it would not affect the satellites or the moon.
Androcles.
For,
| example if we slow down our speed of rotation the hammer-throw starts
| coming closer and closer to the body.
| My explanation for the moon not doing revolution with the same speed as
| earth's rotation (or even planets not taking the same time to revolve
| around the sun) was that as we go away from earth (or sun) the
| gravitational forces decreases and so the angular velocity required by
| moon to counteract also decreases and hence it takes longer time to do
| one complete revolution as compared to earth's rotation.
|
| So, my net explanation was that indeed plane will not rotate with the
| same speed as earth because of decrease in gravitationale attraction but
| not because it can stay still and not revolve around the earth.
|
| I will like to hear the opinion of advice of experts on this.
| Any help in settling the argument will be appreciated.
|
| Thank you,
| Surendra
|
- Next message: Richard Saam: "wave length to vibrational dimension ratio"
- Previous message: No Way: "Re: gravitational force -airplane motion and earths rotation"
- Maybe in reply to: No Way: "Re: gravitational force -airplane motion and earths rotation"
- Next in thread: Nick Maclaren: "Re: gravitational force -airplane motion and earths rotation"
- Reply: Nick Maclaren: "Re: gravitational force -airplane motion and earths rotation"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
