The intensity of radiation reaching the Earth from the Sun is 1350 W/m2.The Earth's radius is 6.4 *106 m.How big a force does this radiation exert on the Earth? (Assume it is all absorbed.)

Question

Quizplus · Accepted Answer

The force exerted by radiation is given by the equation F = P/c, where P is the power of the radiation and c is the speed of light. In this case, the power of the radiation is 1350 W/m2 * 4π(6.4 *106 m)2 = 5.8 * 108 W. The speed of light is 3 * 108 m/s. Therefore, the force exerted by the radiation is 5.8 * 108 W / 3 * 108 m/s = 1.9 * 10-1 N.

The Intensity of Radiation Reaching the Earth from the Sun