why must two coordinates, azimuth and altitude, not just one, be given to specify the location of an object in?

Question

grade 9 science btw

Answer 1

Because to locate a point in a two-dimensional plane requires two coordinates, e.g. x & y. Actually to locate an object in space (three dimensions) requires a third coordinate, distance, but this can be ignored if you're just trying to locate the direction to look for an object.



Astronomers tend to use right ascension (RA) & declination (Dec), rather than altitude & azimuth, to locate an object as RA & Dec do not change w/the observers location or as time passes. Both coordinate systems can be used to locate celestial objects.

Answer 2

Because you need at least two coordinates to define the position of ANY object in a 2 dimensional coordinate system, . Your exact location on the Earth's surface requires BOTH latitude and Longitude, AND you can add altitude or depth as a third coordinate, AND TIME as a fourth coordinate to define your precise location in a FOUR dimensional coordinate system, that includes time.



"...A sphere is a two dimensional surface. Two coordinates are needed to define a point on its surface. The second coordinate used on the Earth is called Longitude. It is made up of a series of great circles running through both poles and set at right angles to the Equator. These circles are not parallel to each other. They are shown on the right sphere above.

Unlike Latitude which has two fixed points (the poles) and a fixed great circle (the Equator), Longitude has no natural zero. All lines of Longitude are identical. The zero line of Longitude is called the Zero Meridian or Prime Meridian. Its position must be decided by international agreement. ...



...The position of an object (like the Sun) is defined by two coordinates. Azimuth is measured clockwise from the North point. Altitude is measured from the horizon to the object. Both are measured in degrees.

Local coordinates are unique for each individual observer. As the Earth rotates on its axis, objects change their position in the sky relative to the observer. This means that the altitude and azimuth of an object change constantly. The altitude and azimuth of an object in the sky depends on





The location of the observer on the Earth

The time of day

The time of year (date)



In particular, the Sun rises from an easterly direction and crosses the Local Meridian. Sunrise is defined as the time when the centre of the Sun is on the horizon while it is moving above the horizon.

In the Northern Hemisphere, the Sun crosses the Meridian due South; in the Southern Hemisphere, the Sun crosses the Meridian due North. Local Solar Noon is the time when the Sun's centre is on the Meridian. The Sun is then at its highest altitude.



At the end of the day the Sun sets in a westerly direction. These motions of the Sun can be used for time keeping. A sundial measures the angle between the Sun and Meridian. The Sun appears to go around the Earth in a 24 hour period. This is a 360° circuit.



24 hours is equivalent to 360°, 1 hour is equivalent to 360 / 24 = 15°.



During a year, the Sun's motion across the sky also changes. This is because the Earth is moving around the Sun. This affects the altitude of the Sun at Noon. The following table shows the effect. ..."



http://www.krysstal.com/coordsystems.html





http://hyperphysics.phy-astr.gsu.edu/hbase/coord.html

Answer 3

There is a missing word in your question... "in the sky" might be what you mean.



A given azimuth coordinate leaves you with a line from directly overhead to a point on the horizon at that azimuth angle from north (northeast would be azimuth 45 degrees, east would be 90 degrees, etc.), but you have a wide range of altitudes (or elevation angles) along that line. So... you need two coordinates. Altitude or elevation angle alone gives you a circle all the way around you just like the horizon, only higher in the sky. Then you need azimuth to know which direction to look at that altitude.



Think that you need latitude and longitude, range and azimuth, "X" and "Y" coordinates....

Answer 4

For 9th grade science, know that there are other co-ordinate systems that can be used not just azimuth and altitude, there is also a celestial coordinate system, cartesian coordiante system but all of them need two references, for example in a cartesian coordiante system we need x and y coordiantes, in celestial coordianate system we need right assention and declination.



So we need to know how far across it is and how far up it is at the very least. This is the minimum amount of information necessary to describe the position of an object.



Actually in 3 dimensional space we need 3 measurements, for example azimuth, altitude and distance from point of origin.



Can you just accept that this is true or at least think hard about how you would find a co-ordinate system that had only one coordiante and how you would describe the position of an object in 2 or 3 dimensions?



A single measurement in more advanced level physics and mathematics is known as a scalar value, it gives you a number and nothing more. Let's say you want to know where I live to come and visit, but I can only tell you where I live in scalar units. I tell you I live exactly 110 miles from your house. That's all the information I can give you. How do you go about finding me? You see how useless that information is? Now if I told you I lived exactly 110 miles due north of where you live, now you have a direction and a distance and you can find me - see why you need two co-ordiantes?



If you can't accept this wait until you get to college level linear algebra then you can have a formal mathematical proof of why you need at least n coordinates to describe a point in n dimensions.