- #1
mastamind518
- 2
- 0
Homework Statement
A 1.6 kg disk with radius 0.63 m is rotating freely at 55 rad/s around an axis perpendicular to its center. A second disk that is not rotating is dropped onto the first disk so that their centers align, and they stick together. The mass of the second disk is 0.45 kg and its radius is 0.38 m. What is the angular velocity of the two disks combined?
rad/s
m1 = 1.6 Kg
r1 = 0.63 m
w1 = 55 rad/s
m2 = 0.45 Kg
r2 = 0.38 m
Homework Equations
conservation of angular momentum
L=mvr
v=rw
The Attempt at a Solution
i set up the equation as... (m1)(v1)(r1)=(m1r1 + m2r2)(v)
where v1 = r1w1 and v is equal to the linear velocity(which should be same for both?)
I solved for v, and then divided by r1, since that's the radius of the whole system, and got an answer of 47.02rad/s. The answer key says the answer is 50 rad/s...
which concept did i get wrong?