2007-11-20 23:27:26 · 11 answers · asked by jib.1990 1 in Science & Mathematics ➔ Astronomy & Space
Any line on a graph that results from the interpretation of a function (equation) is called a 'curve'. If the equation is of the first degree, then the slope of the curve is constant (the line is straight).
On regular surfaces (e.g., the surface of a sphere), the 'straight line' is defined as being the one that gives the shortest distance between two given points. When these lines are viewed from a different perspective, they appear curved.
If you are on the sphere and going along the 'straight line', your direction does not change (you do not turn right nor left). However, if you look at it from outside the sphere, you see that it is part of a great circle. If you 'map' the route through a transformation -- like representing part of the sphere on a Mercator projection chart -- the route will appear curved (that's a result of the transformation).
2007-11-20 23:46:47 · answer #1 · answered by Raymond 7 · 0⤊ 0⤋
On the surface of the Earth, what might look like a straight line is really curved because the Earth is not flat. You cannot go 100 km in a straight line while staying on the ground, because the ground is curved.
In an analogous way, space itself is though to be curved. So even if you don't stay on the surface of Earth your supposedly straight path is curved along with the space it goes through. We cannot see the curvature but we FEEL it. Gravity is a curvature of space.
I realize that is a little hard to grasp. Very hard actually. But that is the theory.
2007-11-21 02:18:40 · answer #2 · answered by campbelp2002 7 · 0⤊ 0⤋
It sounds as if you are one of the numerous people on Y!A who mistakenly believe that the Moon's phases are caused by the shadow of the Earth falling on the Moon. Think about it for a moment, and you'll realize it's complete nonsense. The Moon is moving around the Earth once every 29 days. How often can the Earth cast its shadow on the Moon? Only one brief period close to Full Moon: that's the only time the Sun, Earth, and Moon are lined up the right way. In fact, because of the tilt of the Moon's orbit, this only happens about twice a year. The rest of the time, about 365 days worth, the Earth's shadow comes nowhere near the Moon, and the Moon is in full sunlight. The Moon is a sphere which travels once around the Earth every 29 days. As it does so, it is illuminated from varying angles by the Sun. At New Moon, the Moon is between the Earth and Sun, so that the side of the Moon facing towards us receives no direct sunlight, and is only lit by dim sunlight reflected from the Earth. As it moves around the Earth, the side we can see gradually becomes more illuminated by direct sunlight. After a week, the Moon is 90° away from the Sun in the sky and is half illuminated, what we call First Quarter because it is about a quarter of the way around the Earth. A week after this, the Moon is 180° away from the Sun, so that Sun, Earth and Moon form a line. The Moon is fully illuminated by the Sun, so this is called Full Moon. The Earth's shadow points towards the Moon at this time, but usually the Moon passes above or below the shadow and no eclipse occurs. A week later the Moon has moved another quarter of the way around the Earth, to theThird Quarter position. The Sun's light is now shining on the other half of the visible face of the Moon. Finally, a week later, the Moon is back to its New Moon starting position. Usually it passes above or below the Sun, but occasionally it passes right in front of the Sun, and we get an eclipse of the Sun.
2016-04-05 01:33:44 · answer #3 · answered by Anonymous · 0⤊ 0⤋
You'll have to give us a little more information here, such as the context.
My immediate thought was about great circle routes, which are straight lines on a globe, but appear as curved lines when plotted on a map, because of the map's projection.
2007-11-20 23:39:28 · answer #4 · answered by GeoffG 7 · 0⤊ 0⤋
Well actully a straight line become curve in 3 D geometory. But is straight in 2D. Reason is in 3D there are three axes.And the best example is the earth, suppose you want to go to a place, you go via road that is straight but actully it is curve as earth is sphere.
2007-11-21 03:27:19 · answer #5 · answered by Electrosam 3 · 0⤊ 0⤋
Gravity "bends" everything including light.
As long as there's mass around, there is no such thing as a true straight line.
2007-11-21 00:33:02 · answer #6 · answered by Anonymous · 1⤊ 0⤋
the reason is that the straight line is a part of a cirle we can say that it is an arc. it must have a centre
2007-11-21 02:48:17 · answer #7 · answered by cool 2 · 0⤊ 0⤋
circle with infinite radius is a straight line
2007-11-21 01:16:29 · answer #8 · answered by crazy_frock 2 · 0⤊ 0⤋
it is due to the medium in which the line is present...
2007-11-20 23:35:43 · answer #9 · answered by BadBoy-TellsYouTruth 2 · 0⤊ 0⤋
when the image is shown in the water.
2007-11-20 23:33:52 · answer #10 · answered by ranjith 3 · 2⤊ 0⤋