# PHYSICS

I AM SORRY I JUST HAVE ONE OF THE MOST HORRIBLE TEACHERS, AND I AM TEACHING MYSELF FOR I GET NOTHING IN CLASS.

On an old-fashioned rotating piano stool, a woman sits holding a pair of dumbbells at a distance of 0.565m from the axis of rotation of the stool. She is given an angular velocity of 2.80rad/s , after which she pulls the dumbbells in until they are only 0.200m distant from the axis. The woman's moment of inertia about the axis of rotation is 4.90kg⋅m2 and may be considered constant. Each dumbbell has a mass of 4.95kg and may be considered a point mass. Neglect friction.
Part A
What is the initial angular momentum of the system?

ANSWER IN kg⋅m2/s in the direction of the motion

Part B
What is the angular velocity of the system after the dumbbells are pulled in toward the axis?
ω =

Part C
Compute the kinetic energy of the system before the dumbbells are pulled in.
K = J

Part D
Compute the kinetic energy of the system after the dumbbells are pulled in.K = J

1. 👍 0
2. 👎 0
3. 👁 2,032
1. I initial = 4.90 + .565^2 (4.95*2)
= 4.90 + .319 (9.9)
= 4.90 + 3.16
= 8.06

Ifinal = 4.90 + .2^2(9.9)
= 4.90 + .396
= 5.30 oh my, much less

angular momentum initial and final
= I omega1 = 8.06*2.8
= 5.3*omega2
so
omega 2 = 22.6/5.3 = 4.26 rad/s

Now I think you can do
(1/2) I omega^2 for both

You will find the Ke is higher after she pulls the bells in. She has to put work in to pull the weights in because they are held out by centripetal acceleration.

1. 👍 0
2. 👎 0
2. Thanks! you are a life saver

1. 👍 0
2. 👎 0

## Similar Questions

1. ### Language Arts

1. In ''The Story -Teller,'' the bachelor says that Bertha was ''horribly good.'' What do you think this term means? A. She is so good that she deserves three medals. B. She is horrible-looking but is very well behaved. C. Being

2. ### English

Thank you for your help. 1. She teaches well. 2. She is good at teaching. 3. She is well-teaching. 4. She is ___________. .................. Is #3 not correct? What is suitable adjective which is similar to #1 and #2? What

3. ### english

85. The overriding goal when teaching grammar to EFL students should be to A: improve their communications skills. B: help them successfully name parts of speech. C: improve their abilities to diagram sentences. D: help them

4. ### Help english

Revise the sentences. (1) Revise the following sentence so that the subject and verb of each sentence identify key actors and actions: Currently, the percentage of full-time African-American professors teaching in American

1. ### Math

A. A survey of 110 teachers showed that 28 of them have a second job. B. A survey of 90 teachers showed that 27 of them have a second job. C. A survey of 70 teachers showed that 21 of them have a second job. D. A survey of 80

2. ### Math

A group of teachers and pupils attended a concert. The teachers paid \$1200 altogether and the pupils paid \$640 altogether for their tickets. The price of an adult ticket was \$60 and there were 4 more female teachers than male

3. ### Careers

1. college career counselor working at a community college is part of what career A. administration B. professional support services C. teaching and training D. guidance counseling 2. Which CTS0 is appropriate for future teachers?

4. ### english

How can teaching someone else what you have learned from your reading help you understand it? The other person can pass a test about the information. The other person can tell you whether it is interesting. You will be forced to

1. ### Writing

Please grade, correct,and give feedbacks. Prompt: Colleges reward professors,who have significant research and teaching experience, with tenure. Once tenured, a professor holds his or her job without review and with little danger

2. ### Early Childhood

Which of the following statements regarding the early childhood teacher's science background is true? A It is not necessary for the early childhood teacher to have a science background, she can learn as she goes. B. As long as the

3. ### Designing Specialty Areas

You're designing a space for families. Which of the following would be an important step in developing the space? A. Form a group of current teachers and teaching assistants to design the area. B. Hire a consultant to design the

4. ### vocabulary

Teaching was INNATE to Mrs.Jones as both her parents had been A)CRUEL B)TEACHERS C)STUDENTS D)DULL