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Ch 09: Rotation of Rigid Bodies

Chapter 9, Problem 9

An electric turntable 0.750 m in diameter is rotating about a fixed axis with an initial angular velocity of 0.250 rev/s and a constant angular acceleration of 0.900 rev/s^2. (a) Compute the angular velocity of the turntable after 0.200 s. (b) Through how many revolutions has the turntable spun in this time interval?

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Welcome back everybody. We have a wind driven cyclone that is following a circular pattern here. We're told a couple different things about it, right? We are told that it has um an average diameter of 60 centimeters or 600. m were also told that it's going pretty steady and has a steady angular acceleration of 0.4 to five revolutions per second squared. We're also told that its initial angular velocity is 0.5 revolutions per second. And we are tasked with finding over a time period of 0.750 seconds what the final angular velocity will be and the angular displacement will be Now for this we are going to be using some Kinnah Matic formulas. So first let's go ahead and find this final angular velocity. I'm gonna use the quadratic equation that says that our final angular velocity is equal to our initial angular velocity plus our angular acceleration times time billions of values. Here we have 0.5 plus 0.4 to five times 50.75 which you plug into your calculator. Get a final angular philosophy of 0. revolutions per second. Great. Now let's go ahead and move on to our angular displacement. A formula for angular displacement states that it is equal to our initial angular velocity times time Plus 1/2 hour angular acceleration times, time squared. So let's go ahead and fill into that some values for that too. 0.5 times 0.75 plus one half times 10.4 to times 50.75 squared. Which when you plug this into your calculator, you get 0.495 revolutions. Now we have found the final angular velocity and the angular displacement, which corresponds to answer choice. A thank you all so much for watching. Hope this video helped. We will see you all in the next one.
Related Practice
Textbook Question
Calculate the moment of inertia of each of the following uniform objects about the axes indicated. Consult Table 9.2 as needed. (a) A thin 2.50-kg rod of length 75.0 cm, about an axis perpendicular to it and passing through (i) one end and (ii) its center, and (iii) about an axis parallel to the rod and passing through it.
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Textbook Question
An electric turntable 0.750 m in diameter is rotating about a fixed axis with an initial angular velocity of 0.250 rev/s and a constant angular acceleration of 0.900 rev/s^2. (c) What is the tangential speed of a point on the rim of the turntable at t = 0.200 s?
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Textbook Question
A wheel is rotating about an axis that is in the z-direction. The angular velocity ω_z is -6.00 rad/s at t = 0, increases linearly with time, and is +4.00 rad/s at t = 7.00 s. We have taken counterclockwise rotation to be positive. (a) Is the angular acceleration during this time interval positive or negative?
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Textbook Question
A wheel is rotating about an axis that is in the z-direction. The angular velocity ω_z is -6.00 rad/s at t = 0, increases linearly with time, and is +4.00 rad/s at t = 7.00 s. We have taken counterclockwise rotation to be positive. (c) What is the angular displacement of the wheel at t = 7.00 s?
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Textbook Question
An electric fan is turned off, and its angular velocity decreases uniformly from 500 rev/min to 200 rev/min in 4.00 s. (a) Find the angular acceleration in rev/s^2 and the number of revolutions made by the motor in the 4.00-s interval. (b) How many more seconds are required for the fan to come to rest if the angular acceleration remains constant at the value calculated in part (a)?
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