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Lamebert
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Homework Statement
A space station has the form of a hoop of radius R = 15 m, with mass M = 1000 kg. Initially its center of mass is not moving, but it is spinning with angular speed ωi = 4 rad/s. A small package of mass m = 22 kg is thrown at high velocity by a spring-loaded gun at an angle θ = 25 ◦ toward a nearby spacecraft as shown. The package has a speed v = 380 m/s after launch. What is the space station’s rotational speed ωf after the launch? You may ignore the weight of the package in calculating the moment of inertia of the space station. Answer in units of rad/s
Homework Equations
Krot = 1/2 Iω2
L = Iω
τ = rfsinθ
Ktrans = 1/2mv2
I = mr2
The Attempt at a Solution
[STRIKE]I tried to use kinetic energy for this, and I got an answer that seems reasonable, but this is the torque/rotational momentum chapter so I don't want to submit an answer until I think it's right.
I used the energy principle to solve this:
Krot,i = Krot,f + Ktrans
Since they provide us with an angle, I can't help but think torque is probably involved. There wasn't a way to find the force applied by the box on the wheel, so I decided torque wasn't really valid to use. Another point of contest is the fact that the station could gain some of the translational kinetic energy. I was thinking about it, and if the package was shot off at a 90 degree angle, all the energy would be transmitted to the translational kinetic energy of the station.
Now that I think about it, it may be smart to apply only the y component towards reduction of the[/STRIKE] ... blah blah blah I stopped typing and took a second look.
I used the y component of the kinetic energy of the block as reduction of the rotational kinetic energy of the station. The rest will be applied as translational kinetic energy. So pretty much:
Krot,i = Krot,f + Ktrans,block sinθ
Assuming I'm competent enough to use a calculator, some validation on whether or not this line of thought is proper would be nice. Thanks :)
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