Answer:
Actually it's 2.50 m/s, sorry
Step-by-step explanation:
It is solved by using momentum conservation equation
combined mass of crow and feeder = 450+670=1120 gm
let the recoil speed of feeder be v m/s
Then applying momentum conservation we get;
1120×1.5 = 670×v
v= 2.50 m/s
the speed at which the feeder initially recoils backwards = 2.50 m/s