A high-speed flywheel in a motor is spinning at 500 rpm when a power failure suddenly occurs. The flywheel has mass 39.0 kg and
diameter 80.0 cm. The power is off for 32.0 s and during this time the flywheel slows due to friction in its axle bearings. During the time the power is off, the flywheel makes180 complete revolutions.
A. At what rate is the flywheel spinning when the power comes back on? (rad/s)
B. How long after the beginning of the power failure would it have taken the flywheel to stop if the power had not come back on? (s)
C. How many revolutions would the wheel have made during this time?
A. At what rate is the flywheel spinning when the power comes back on? (rad/s)
B. How long after the beginning of the power failure would it have taken the flywheel to stop if the power had not come back on? (s)
C. How many revolutions would the wheel have made during this time?
1 answer:
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Answer:
Ek = 1705.28 [J]
Explanation:
In order to solve this problem, we must remember that kinetic energy can be calculated by means of the following equation.
where:
m = mass [kg]
v = velocity [m/s]
Ek = kinetic energy [J] (Units of Joules)
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The difference in Kinetic energy is equal to:
Ek = 2025 - 319.72
Ek = 1705.28 [J]