00:01
In problem 954, mass 1 is 20 kilograms.
00:06
There's an undamped isolator and 90 % isolation over 1 ,000 to 3 ,000 rpm.
00:11
For an undamped isolator, t is equal to 1 over r squared minus 1.
00:16
R is omega over the natural frequency, and r is positive.
00:21
90 % isolation means t is equal to 0 .10.
00:26
So 0 .10 is equal to 1 over r squared minus 1 .1 .1.
00:33
And so r squared minus 1 would be 1 over 0 .1 which is 10 so r squared is 11 so r is a square root of 11.
00:43
To guarantee isolation over the whole range use the lowest speed 1 ,000 rpm as the worst case.
00:50
So omega min would be 2 pi times 1 ,000 over 60 which is 104 .72 radiance per second...