(adsbygoogle = window.adsbygoogle || []).push({}); The moon has a diameter of 3.48 x 10^6 m and is a distance of 3.85 x 10^8m from the earth. The sun has a diameter of 1.39 x 10^9 m and is 1.50 x 10^11 m from the earth.

(a.)What are the angles (in radians) subtended by the moon and the sun, as measured by a person standing on the earth.

Because the large planetary masses are so very far away, we can assume that s = diameter

Θ = s/r

For the moon:

S = 3.48E6 m

r = 3.85E8 m

Θ = s/r = 3.48E6/3.85E8

Θ = 0.009038961 radians

For the sun:

S = 1.39E9 m

r = 1.50E11 m

Θ = s/r = 1.39E9/1.50E11

Θ = 0.0092666667 radians

(b.)Based on the answers to part (a.), is a total eclipse of the sun really "total"?

No, because the angles are not perfectly equal.

(c.)What is the ratio (as a percentage) of the apparent circular area of the moon to the apparent circular area of the sun?

For part C, do I just use Pi(radius)^{2}and compare the two areas? I just don't understand stand what they mean by "apparent" circular area. Is this problem just to emphasize how much larger the sun is than the moon?

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# Homework Help: Substended angle, rotational kinematics

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