00:01
So we have a helicopter moving in a circle, and the radius of this circle is 400 meters.
00:11
And we're told that the helicopter is moving with a tangential velocity of 40 meters per second.
00:19
And the mass of the helicopter is 4 ,000 kilograms.
00:23
They say 4 megagrams, but that's 4 ,000 kilograms.
00:26
And what we want to know is what kind of lift force is required.
00:31
So that's basically the force perpendicular to the rotors, such that we can maintain this speed, provided that we're moving at a certain angle.
00:42
So how do we do this? well, first off, what we really need is notice that the lift force is going to have two components.
00:49
It's going to have a component this way and a component upwards.
00:53
And some together, those give you this diagonal component.
00:56
So the component that provides the centripetal force is going to be the what we call the lift force times the sign of this angle, right? this is our centripetal force effectively...