일반물리학 2 — Electromagnetic Waves: Problem 28

28 Radiation from the Sun reaching Earth (just outside the atmosphere) has an intensity of $1.4\text{ kW/m}^2$. (a) Assuming that Earth (and its atmosphere) behaves like a flat disk perpendicular to the Sun’s rays and that all the incident energy is absorbed, calculate the force on Earth due to radiation pressure. (b) For comparison, calculate the ratio of that force to the force due to the Sun’s gravitational attraction.