Question

pample
Halecting
= 6.48 x 10
8.4 Light with an energy flux of 18 W/cm falls on a non-
nergy being
surface at normal incidence. If the surface has an area of
get warm).
r hand but 30 cmfind the average force exerted on the surface during a 30
is extremely
minute time span.
n scientists solution
ressure of the total energy falling on the surface is
U = (18 W/cm') * (20 cm') < (30 x 60)
he order of
o radiation
therefore, the total momentum delivered (for complete absorption) is
ves stems
U 6.48x10'J
= 2.16 x 10 kg m/s
ther. The
3x108m/s
gy. Light
ssible on
The average force exerted on the surface is
P
2.16x10-3
=1.2x10 N
0.18x10
ency How will your result be modified if the surface is a perfect reflector?
cular
Em
P.
EXAMPLE 8. +
fe

Answer 1

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