On a safari, you are spear fishing while wading in a river. You observe a fish g
ID: 1490843 • Letter: O
Question
On a safari, you are spear fishing while wading in a river. You observe a fish gliding by you. If your line of sight to the fish is 63° below the horizontal in air, and assuming the spear follows a straight line path through the air and water after it is released, determine the angle below the horizontal that you should aim your spear gun in order to catch dinner. Assume the spear gun barrel is 1.6 m above the water surface, the fish is 1.1 m below the surface, and the spear travels in a straight line all the way to the fish.
Explanation / Answer
= 63degrees,h= 1.6 m , d= 1.1 m
IA = 35.186 W/m^2
refractive index of air n1 =1
refractive index of water n2 =1.33
Ue pictrorial representation to express the aiming angle alpha
alpha = arctan((h+d)/(L+l))
L = h tan1 , l = dtan2
from snells law n1 sin1 = n2 sin2
from above retlaitons we get
alpha = arctan ((h+d)/htan1 +dtan(arcsin(n1sin1/n2)))
1 is complement of 63, 1 =90 -63 = 27 degrees
alpha = arctan ((1.6+1.1)/htan27 +dtan(arcsin(1*sin27s/1.33)))
alpha = 65.78 degrees