Question

m. 2. On July 3, 2020, the comet NEOWISE made its closest approach to the Sun at a distance of 4.3 x 1010 m (a) If the average power output of the Sun is P = 3.8 x 1026 W, what is the radiation pressure on the comet at this point in its orbit? Assume that the comet is a perfect reflector. (b) The comet's nucleus is estimated to be about 5 km in diameter. What is the force from the solar radiation on the nucleus? (e) Compare the radiation force to the gravitational force between the Sun and the comet's nucleus.

Answer 1

(A)

First, we find the intensity

I = P / 4$\pi$r²

I = 3.8e26 / 4$\pi$ * 4.3e10²

I = 16354.5 W/m²

so,

radiation pressure for a perfect reflector,

P = 2I / c

P = 2 * 16354 .5 / 3e8

P = 1.1e-4 Pa

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(B)

force = pressure * area

force = 1.1e-4 * $\pi$ * 2500²

force = 2141 N

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(C)

gravitational force is found as

F = GMm / r²

but mass of neowise is not given