Angus Goodwin
Jan 12, 2025
how many degrees are there in a sphere?
What is the total number of degrees in a sphere?
10 Answers
The steradian (discussed above) is the official SI unit of a solid angle. A plane angle in radians is defined as the arc length divided by the radius so 1 radian is an angle with an arc lenght of 1 radius. One steradian is defined as the solid angle that covers and area on a sphere equal to the radius squared so there are 4*pi steradians in a sphere. You can define square degrees (astronomers use them sometimes) based on the definition of steradians. Nominally, a square degree is the area covered by a 1 degree x 1 degree piece of the sky. Since there are 180/pi degrees per radian it follows that there are (180/pi)^2 square degrees per steradian. Or (180/pi)^2 * 4 * pi = 41250 square degrees in a sphere.
We can't say how many degrees there are in a sphere, any more than we can say how many feet there are in an acre. Feet are a measure of length, and an acre is an area, not a length. You can't measure an area with a tape measure. Likewise, degrees are a measure of an angle; you can sweep out a circle by swinging a line through an angle of 360 degrees. But you can't sweep out a sphere by swinging a line through some angle, so angle measure won't do to measure a sphere.
Let's think more about the analogy to length versus area. We can measure area in *square* feet. Is there anything like "square degrees" that we can use to measure a sphere? Yes, there is! But instead of degrees, we start with radians, a different measure of angles. We come up with something that could perhaps be called "square radians." Squares won't really enter into it, though, so instead we call the unit a "steradian" (like "stereo radian"; stereo is from the Greek for solid, or 3-dimensional). We say that it is a measure of "solid angle."
Oct 19, 2024
a degree is a angular measurement on a plane. A sphere consists of multiple planes. A degree is not a unit of volume. There is no 3d equivalent to a degree. If you have a specific problem on a worksheet you are stuck on, try posting it. And please don't be rude..
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You need steel's coefficient of linear thermal expansion. Which is about 1×10^-5/°C Simply multiply: 2cm×1×10^-5/°C × 110°C = .0022cm New radius = 2.0022 cm Volume coeficient is approximately 3 time the linear coefficient Volume at 40C = 4/3π(2cm)³ = 33.51 cm³ Volume change at 150C = 33.51cm³×3×10^-5/C×110C = 1.106cm³ New volume = 33.51cm³+1.106cm³ = 34.616cm³
If you mean "square degrees", then its about 41,253 I believe:
4*pi*(180/pi)^2
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