00:03
Okay, so for this problem, we're given a helicopter that has four blades, and each of them is 3 .4 meters long from the center of the blade tip.
00:16
So that means we could take r to be a distance between the center and the tip of the blade.
00:21
So that's our r value then.
00:22
So r is going to be 3 .40 meters.
00:26
And we're also given an angular velocity of 550 revolutions per minute.
00:31
And then we're being asked to find the linear velocity v in part a, and then the radial acceleration in part b.
00:40
Okay, so first let's find the linear velocity v.
00:44
So linear velocity is equal to the angle velocity, which is omega, times r, the distance here.
00:56
Okay, but we first want to make sure that the anger velocity has the proper units.
01:00
So in order to use this equation, we want the angle of velocity to be in units of radians per second.
01:08
So now we have revolutions per minute, so we'll convert it then.
01:35
So we know that in one revolution, we're going to have 2 pi radians.
01:40
So multiply by 2 pi per revolution.
01:55
And we know there's 60 seconds in a minute, so multiply by 1 minute over 60 seconds.
02:14
So now the minutes cancel out, and the revolutions cancel out.
02:22
So we just have 550 times 2 pi divided by 60 seconds.
02:26
So i'm going to get 57 .6.
02:42
And now the units are going to be in radiance per second.
02:46
Because i have radians in the numerator here, and then seconds in the denominator.
02:54
So now i can plug this value in the equation for the linear velocity v here.
03:02
Okay...