# College Physics

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During a rescue operation, a 5600-kg helicopter hovers above a fixed point. The helicopter blades send air downward with a speed of 69 m/s. What mass of air must pass through the blades every second to produce enough thrust for the helicopter to hover?

• College Physics -

Strictly speaking, you also need to know the vertical velocity component of the air entering the blades from above. It is not zero.

They probably want you to use
Weight = V * dm/dt,

and solve for dm/dt, the air mass flow through the blades, but this is a flawed problem.

I do not endorse their answer

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