Answer:
for the birds to be able to stay vertical in flight without falling down to earth, they must produce a lift that will counteract their weight
for the small bee humming bird,
mass = 1.6 g = 1.6 x kg
weight of the bird under acceleration due to gravity = mg
where g = acceleration due to gravity = 9.81 m/s^2
weight of the bird = 1.6 x x 9.806 = 0.0156 ≅ 0.016 N
for this bird to maintain flight, the least lift upward, it must generate must be equal to its weight downwards, i.e
lift = weight
therefore,
lift = <em>0.016 N</em>
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For the bustard of Europe and Asia,
mass = 21 kg
weight of the bird under acceleration due to gravity = mg
weight of the bird = 21 x 9.806 = 205.9 N
lift = weight = <em>205.9 N</em>
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<em>lift generated is proportional to the wing surface area according to the lift equation</em>
L = Cs x p x x S
where L = lift
C = lift coefficient
p = density of air
v = relative velocity of bird and air
S = surface are of the wing.
<em>The great bustard will have a proportionally larger wing area to hold its weight in flight</em>
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