How much does a 280 g bird slow down after eating a 15g insect?

Question

A 280 g bird flying along at 6.0 m/s sees a 15 g insect heading straight toward it with a speed of 30 m/s. The bird opens its mouth wide and enjoys a nice lunch. Can you help me to find the bird's speed immediately after swallowing?

Answer 1

bird                                                       insect

mass    m1                                               m2

initial velocity    u1                                   u2

final velocity  v1                                       v2

apply law of conservation of momentum

m1 x  u1+ m2 x u2 = m2 x v2 + m1 x v1

280 x 6 + 15 x 30 = 15 x v  +  280 x v   [ the velocity of both the insect and bird will be same after swallosing the insect]

therefore

v1=v2=v

now calculate v

it will be 2.687m/s.