00:01
Problem 11 .62, we have an acrobat doing a quadruple somersault and then getting caught by his partner.
00:08
For the first and last quarter of a revolution, he's in this sort of outstretched position, and then for most of it, he's in this tucked position.
00:26
And what we want to find, given that this whole thing lasts for 1 .87 seconds, we want to find out what omega -2 is here for his angular speed for most of the jump.
00:42
So the angular momentum has to be conserved.
00:53
So i -1 -o -mega -1 equals i -2, omega -2.
01:05
Now, we can write the total time of flight, which we know.
01:17
So hopefully it will be equal to an expression that has something useful in it.
01:25
It's going to be equal to the angle he goes through in position 1 divided by how fast he's doing that, plus the angle he goes through in position 2 divided by how fast he's going while doing that.
01:46
So rearranging this, or rather using our conservation of momentum here, we can replace omega -1 with i2 omega -2 divided by i -1 this one already has our omega -2 that we want and so then combining some terms we get this expression which looks pretty nice so theta 1 is a quarter revolution plus a quarter revolution so that's half a revolution and so then this will be the remaining three and a half revolutions.
02:58
This will be pi radians...