Examples of circumference in the following topics:
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- Using basic geometry, Greek mathematician Eratosthenes determined the circumference of the Earth within 0.4% error of today's value.
- Eratosthanes sought to know the circumference of Earth.
- To measure its circumference, he devised a method that used the rays of sunlight that hit Earth which he assumed arrive parallel.
- But the circumference of a sphere equals π times its diameter:
- Thus his measurement of the Earth circumference (some 2000 years ago) was in error: Less than actual by only one-tenth of a percent.
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- We know that for one complete revolution, the arc length is the circumference of a circle of radius r.
- The circumference of a circle is 2πr.
- The arc length Δs is described on the circumference.
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- Assuming that an integral multiple of the electron's wavelength equals the circumference of the orbit, we have:
- The third and fourth allowed circular orbits have three and four wavelengths, respectively, in their circumferences.
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- By assuming that the electron is described by a wave and a whole number of wavelengths must fit along the circumference of the electron's orbit, we have the equation:
- (c) If the wavelength does not fit into the circumference, the electron interferes destructively; it cannot exist in such an orbit.
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- This is because the center tracks are smaller in circumference and therefore can be read quicker.
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- The arc length Δs is described on the circumference.
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- Electromagnets are employed for many uses: from a wrecking yard crane that lifts scrapped cars, to controlling the beam of a 90-km-circumference particle accelerator, to the magnets in medical imaging machines (for other examples see ).
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- You can prove this yourself by remembering that the circumference of a circle is 2*pi*r, so if the object traveled around the whole circle (one circumference) it will have gone through an angle of 2pi radians and traveled a distance of 2pi*r.
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- The arc length Δs is described on the circumference.
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- Now the average speed v is the circumference divided by the period: