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Sever21 [200]
3 years ago
6

A fisherman in a stream 39 cm deep looks downward into the water and sees a rock on the stream bed. How deep does the stream app

ear to the fisherman
Physics
1 answer:
Diano4ka-milaya [45]3 years ago
6 0

Answer:

30cm

Explanation:

assume that the eyes are substantially above the water so that sin(theta) is approximately theta.

( small angle approximation).

The point at which a ray leaving the fish hits the surface of the water is x to the side of the centreline and the depth of the water is d

x/d = sin( angle of incidence)

if the apparent depth of the water is h then

x/h = sin( angle of refraction)

and applying snells law

1 sin ( theta air) = 1.33 sin( theta water)

1 * x/h = 1.33 * x/d

d/h = 1.33

or h/d = 1/1.33

h/39 = 1.33

h = 39 /1.33 so that is the apparent depth of the stream assuming:-

1. Your eyes are almost directly overhead

and

2. your eyes are a significant distance above the surface of the water.

x/d = 1.33 x/h

h/d =39/1.3

= 30cm

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The machine in the figure is ideal and an effort force of
DENIUS [597]

Answer:

1.5 m

Explanation:

Let the distance from the box to the pivot be c.

Let the distance from the pivot to the effort be y.

From the question given above, the following data were obtained:

Effort force (Fₑ) = 7 N

Force of resistance (Fᵣ) = 14 N

Distance from the box to the pivot (c) = 0.75 m

Distance from the pivot to the effort (y) =?

Clockwise moment = Fₑ × y

Anticlock wise moment = Fᵣ × c

Clockwise moment = Anticlock wise moment

Fₑ × y = Fᵣ × c

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Answer:

33.516 kJ

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