It is known that E-M waves, including light, exert a \'\'radiative\'\' pressure

Question

It is known that E-M waves, including light, exert a ''radiative'' pressure p=I/c on a non-reflective surface. Assuming that the Sun radiates with an intensity of 1386 W/ m^2 near Earth (149 million kilometers from the center of the Sun), what is its intensity in the vicinity of Mars's orbit, which has an average radius of 230 million kilometers? (Ans.: 582 W/m^2 ) A 10,000 kg spacecraft located near Mars has a square ''solar sail'' of side L. What should be the value of L for the radiative force to cancel the Sun's gravitational pull?

Explanation / Answer

intensity at earth = Iearth = 1386 W/m2

intensity at mars = Imars

distance of earth = rearth = 149 millon km

distance of mars = rmars = 230 millon km

Using the formula ::

Iearth/Imars = rmars2 / rearth2

(1386)/Imars = (230)2 / (149)2

Imars = 582 W/m2

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.