Physics 211
Week 8
Rotational Kinematics and Energy: Space Station
A space station is constructed in the shape of a wheel 22m in diameter, with essentially all its
weight (5.0 x 10
5
kg) at the rim.
Once the space station is completed, it is set rotating at a rate
such that an object at the rim experiences a radial acceleration equal to the Earth's gravitational
acceleration g, thus simulating Earth's gravity.
To accomplish this, two small rockets are
attached on opposite sides of the rim, each able to provide a 100N force.
How long will it take to
reach the desired rotation rate and how many revolutions will the space station make in this
time?
The space station will start from rest. Torque from the rockets will cause an angular acceleration
until the desired rate of rotation is achieved.
Begin by finding the desired rotation rate where the
centripetal acceleration is equal to the earth’s acceleration.
Next, set the torque created by the
applied force of the rockets equal to the moment of inertia times the angular acceleration to find
the acceleration of the wheel; you may ignore the mass of the rockets.
Then you can use
rotational kinematics with the angular acceleration and angular velocity to find the time it takes
and the number of revolutions the station will make to reach the desired rate of rotation.
You
should obtain a time of 2.6x10
4
seconds and a total of 1.95x10
3
revolutions.
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View Full DocumentPhysics 211
Week 8
Rotational Kinematics and Energy: Rotating Tip
In the Physics 211 Laboratory one group of students has decided to pursue their own
experiments.
They make a simple pendulum from a weight attached to a string of length L.
They attach the other end of the string to a fixed support.
They hold the weight with the string
taut and horizontal and then released it.
With their motion sensor they measure the speed of the
weight as the string passes through the vertical.
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 Spring '09
 TonyLiss
 Energy, Kinetic Energy, Potential Energy, space station

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