Question

A bird sees a fish swimming in a pond with a velocity of $5m/s$ horizontally. If the fish is vertically below the bird initially, then in order to catch the fish, at what angle with the horizontal does the bird need to come, if the velocity of the bird is $10m/s$? (Assuming that there is no reflection of light)

• A. ${50}^{\circ }$
• B. ${60}^{\circ }$
• C. ${58}^{\circ }$
• D. ${40}^{\circ }$

Answer 1

The correct option is B ${60}^{\circ }$

Let’s assume the bird flies, making an angle $\theta$ with the horizontal.


In order to catch the fish, the horizontal component of velocity of the bird must equal the velocity of swimming of the fish.

i.e $v\cos \theta =5.0m/s$
$10\cos \theta =5$
$\cos \theta =5/10=0.5$
$\theta ={60}^{\circ }$