I need expert help to solve the given question:

Question: A bacterium using its flagellum as propulsion can move through liquids at a rate of 0.003 m/s. For a 50-um long bacterium, that is the equivalent of 60 cell lengths per second. Bacteria of that size have a mass of approximately 1 x 10-12 g. The viscous drag on a swimming bacterium is so great that if it stops beating its flagellum it will stop within a distance of 0.01 nm.

Part A: What amount of force must the flagellum generate to propel the bacterium at a constant velocity of 0.003 m/s?

Don't just give me the answer, explain your steps as well.