Question

In the 25 ft Space Simulator facility at NASA's Jet Propulsion Laboratory, a bank of overhead arc lamps can produce light of intensity 2500 W/m2 at the floor of the facility.
A) Find the average radiation pressure (in pascals) on a totally absorbing section of the floor.B) Find the average radiation pressure (in atmospheres) on a totally absorbing section of the floor.C) Find the average radiation pressure (in pascals) on a totally reflecting section of the floor.D) Find the average radiation pressure (in atmospheres) on a totally reflecting section of the floor.

Answer 1

Answer:

a) 8.33 x 10^-6 Pa

b) 8.23 x 10^-11 atm

c) 1.67 x 10^-5 Pa

d) 1.65 x 10^-10 atm

Explanation:

Intensity of the light $I$ = 2500 W/m^2

speed of light $c$ = 3 x 10^8 m/s

a) we know that the pressure for for a totally absorbing surface is given as

$P_{abs}$ = $I/c$ = 2500/(3 x 10^8) = 8.33 x 10^-6 Pa

b) 1 atm = 101325 Pa

$P_{abs}$ = (8.33 x 10^-6)/101325 = 8.23 x 10^-11 atm

c) for a totally reflecting surface

$P_{ref}$ = $2I/c$ = twice the value for totally absorbing

$P_{ref}$  = 2 x 8.33 x 10^-6 = 1.67 x 10^-5 Pa

d)  1 atm = 101325 Pa

$P_{ref}$ = 2 x 8.23 x 10^-11  = 1.65 x 10^-10 atm