A fish is rising up vertically inside a pond with velocity of 4 cm / s, and notices a bird, which is diving vertically downward and its velocity appears to be 16 cm / s (to the fish). What is the real velocity (in cm / s ) of the diving bird, if refractive index of water is 4 / 3.

Question

A fish is rising up vertically inside a pond with velocity of 4 cm / s, and notices a bird, which is diving vertically downward and its velocity appears to be 16 cm / s (to the fish). What is the real velocity (in cm / s ) of the diving bird, if refractive index of water is 4 / 3. (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/a38daa9cac9b61331e677f4d81d654b9-.png" /> ( v I - v S /4 / 3)=( v 0- v S /1) v I =(4 v 0/3) v I - v f =16 =(4/3) v 0+4=16 (4/3) v 0=12 ⇒ v 0=9 cm / s

Q. A fish is rising up vertically inside a pond with velocity of $4 c m / s$ , and notices a bird, which is diving vertically downward and its velocity appears to be $16 c m / s$ (to the fish). What is the real velocity (in $c m / s$ ) of the diving bird, if refractive index of water is $4/3$ .

$\frac{v _{I} - v _{S}}{4/3} = \frac{v _{0} - v _{S}}{1}$
$v_{I} = \frac{4 v _{0}}{3}$
$v_{I} - v_{f} = 16$
$= \frac{4}{3} v_{0} + 4 = 16$
$\frac{4}{3} v_{0} = 12$
$\Rightarrow v_{0} = 9 c m / s$

Q. A fish is rising up vertically inside a pond with velocity of 4cm/s, and notices a bird, which is diving vertically downward and its velocity appears to be 16cm/s (to the fish). What is the real velocity (in cm/s ) of the diving bird, if refractive index of water is 4/3.

4/3vI​−vS​​=1v0​−vS​​ vI​=34v0​​ vI​−vf​=16 =34​v0​+4=16 34​v0​=12 ⇒v0​=9cm/s

Q. A fish is rising up vertically inside a pond with velocity of $4 c m / s$ , and notices a bird, which is diving vertically downward and its velocity appears to be $16 c m / s$ (to the fish). What is the real velocity (in $c m / s$ ) of the diving bird, if refractive index of water is $4/3$ .

$\frac{v _{I} - v _{S}}{4/3} = \frac{v _{0} - v _{S}}{1}$
$v_{I} = \frac{4 v _{0}}{3}$
$v_{I} - v_{f} = 16$
$= \frac{4}{3} v_{0} + 4 = 16$
$\frac{4}{3} v_{0} = 12$
$\Rightarrow v_{0} = 9 c m / s$