The rotating blades of a hovering helicopter sweep out an area of radius 4m imparting a downward velocity of 12m/s to the air displaced. A) find the mass of the helicopter.
B) the speed of rotation of the blades of the helicopter is increased so that the air now has a downward velocity of 13m/s. find the upward acceleration of the helicopter

During the experiment if you could triple the breakaway magnetic force with all other quantities left unchanged, what is the new value for the critical velocity if it was v0 (initial velocity), initially? (b) now if you halved the radius with all other quantities left unchanged, what is the new critical velocity if it was v0 (initial velocity), initially? (c) if during the experiment, critical velocity quadrupled with all other quantities left unchanged, what is the new breakaway force if its magnitude was initially f0,?