Answer:
Intensity of beam 18 feet below the surface is about 0.02%
Explanation:
Using Lambert's law
Let dI / dt = kI, where k is a proportionality constant, I is intensity of incident light and t is thickness of the medium
then dI / I = kdt
taking log,
ln(I) = kt + ln C
I = Ce^kt
t=0=>I=I(0)=>C=I(0)
I = I(0)e^kt
t=3 & I=0.25I(0)=>0.25=e^3k
k = ln(0.25)/3
k = -1.386/3
k = -0.4621
I = I(0)e^(-0.4621t)
I(18) = I(0)e^(-0.4621*18)
I(18) = 0.00024413I(0)
Intensity of beam 18 feet below the surface is about 0.2%
I think it’s 250,000 ft./hr
U=0ms^-1
t=12s
a=-9.81ms^-1
v=?
from an equation,v=u+at
v=0+(-9.81)(12)
=-117.72ms^-1
Explanation:
Newton's second law of motion states that the external force is directly proportional to the rate of change of momentum. Mathematically, Newton's second law of motion is given by :
F = ma
Where
m is the mass and a is the acceleration
If there is a smaller mass, it would need a weaker force to accelerate it as the force is directly proportional to the mass. Hence, the correct option is (d).
