030  Rotational Motion

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course Phy 241

7/28 12:55 am

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Question: `q001. Note that this assignment contains 5 questions.

If an object rotates through an angle of 20 degrees in five seconds, then at what rate is angle changing?

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Your solution:

20 degrees / (5 seconds)

= 4 deg / sec

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Question: `q002. What is the average angular velocity of an object which rotates through an angle of 10 `pi radians in 2 seconds?

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Your solution:

omega = `d`theta / `dt

omega = 10 `pi radians / 2 seconds

omega = 5 `pi rad/s

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Question: `q003. If an object begins with an angular velocity of 3 radians / sec and ends up 10 seconds later within angular velocity of 8 radians / sec, and if the angular velocity changes at a constant rate, then what is the average angular velocity of the object? In this case through how many radians this the object rotate and at what average rate does the angular velocity change?

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Your solution:

(8 rad/s + 3 rad/s) / 2

= 5.5 rad/s

5.5 rad/s * 10 s

= 55 rad

(5 rad / sec ) / (10 sec)

= .5 rad/s^2

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Question: `q004. If an object starts out with angular velocity 14 rad/s and accelerates at a rate of 4 rad/s^2 for 5 seconds, then at what rate is the object rotating after the 5 seconds? Through how many radians will the object rotate during this time?

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Your solution:

Angular Velocity

(4 rad/s^2) (5s)

= 20 rad/s

Total Angular Velocity

14 rad/s + 20 rad/s

= 34 rad/s

Average Angular Velocity

(14 rad/s + 34 rad/s) / 2

= 24 rad/s

d`theta = (24 rad/s) ( 5 sec)

d theta= 120 rad

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Self-critique (if necessary):

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Self-critique rating:

If you understand the assignment and were able to solve the previously given problems from your worksheets, you should be able to complete most of the following problems quickly and easily. If you experience difficulty with some of these problems, you will be given notes and we will work to resolve difficulties.

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Question: `q005. A rotating object starts with an angular velocity of 12 radians / second and accelerates through 60 radians in 6 seconds. What are its final angular velocity and angular acceleration?

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Your Solution:

(60 radians/6 sec)

= 10 radians/sec

(12 radians/sec + 10 radians/sec) / 2

= 22 radians/sec / 2

= 11 radians/sec

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Self-critique (if necessary):

------------------------------------------------

Self-critique rating:

If you understand the assignment and were able to solve the previously given problems from your worksheets, you should be able to complete most of the following problems quickly and easily. If you experience difficulty with some of these problems, you will be given notes and we will work to resolve difficulties.

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Question: `q005. A rotating object starts with an angular velocity of 12 radians / second and accelerates through 60 radians in 6 seconds. What are its final angular velocity and angular acceleration?

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Your Solution:

(60 radians/6 sec)

= 10 radians/sec

(12 radians/sec + 10 radians/sec) / 2

= 22 radians/sec / 2

= 11 radians/sec

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Self-critique (if necessary):

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Self-critique rating:

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