A student sits on a rotating stool holding two 3.0 kg objects. When his arms are extended horizontally, the objects are 1.0 m from the axis of rotation, and he rotates with an angular speed of 0.75 rad/s. The moment of inertia of the student plus stool is 3.0 kg·m2 and is assumed to be constant. The student then pulls the objects horizontally to 0.50 m from the rotation axis.
(a) Find the new angular speed of the student.
1Your answer is correct. rad/s
l1=I+2MR^2
I1 = 3.0+2*3.0*1² = 9.0 kg?m²
I2 = 3.0+2*3.0*.50² = 4.5 kg?m²
a) L1 = L2 -> .75*9.0 = w2*4.5 -> w2 = 1.5 rad/sec
Ok, this is what I found online. Why do I add the moment of inertia to 2MR^2?
I can't find anything in my notes that explains this, any explanation would be very much appreciated.
Thank you,
Zach
(a) Find the new angular speed of the student.
1Your answer is correct. rad/s
l1=I+2MR^2
I1 = 3.0+2*3.0*1² = 9.0 kg?m²
I2 = 3.0+2*3.0*.50² = 4.5 kg?m²
a) L1 = L2 -> .75*9.0 = w2*4.5 -> w2 = 1.5 rad/sec
Ok, this is what I found online. Why do I add the moment of inertia to 2MR^2?
I can't find anything in my notes that explains this, any explanation would be very much appreciated.
Thank you,
Zach