Answer:
Air speed of bird is
mph
Explanation:
let the speed of the bird in still air be "X"
Speed of the bird when it flies in the direction of flow of wind 
Speed of the bird when it flies in the opposite direction of flow of wind 
The total time taken is equal to
minutes
hours
The distance in miles is equal to
miles

On solving the above equation, we get -

Air speed of bird is
mph
Force is equal to mass times acceleration, therefore acc. is equal to Force divided by mass.
500 N /50kg equals 10m/s^2.