A bird of mass 0.8kg hovers upwards by beating the mass of effective area 0.5m^2. (i) what is its upthrust? (ii) estimate the velocity imparted to the air by beating of the wings assuming the density of air at STP to be 1.3kg/m^3.

Answer 1

upward thrust= weight of bird

massair*velocity=thrust*deltatime

massair/time *velocity=thrust

densityair*volume*velocity

densityair*area*velocity*time*veloity=thrust*time

velocity^2=thrust/(densityair*area)