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anonymous

  • one year ago

Medal award! Can someone help me? If this circle (disc) spins 20 revolutions per minute, what is the angular speed? what would the linear speed be at point p in m/s?

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  1. anonymous
    • one year ago
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  2. Curry
    • one year ago
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    2.1 = angular speed.

  3. Curry
    • one year ago
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    37.7 linear speed.

  4. anonymous
    • one year ago
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    how do you set it up?

  5. Curry
    • one year ago
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    well for linear speed, it is [circumference times 20] divided by 60

  6. Curry
    • one year ago
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    so, wait soryr. i calcualted wrong units.

  7. Curry
    • one year ago
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    it'd be 10.47 for linear speed.

  8. Curry
    • one year ago
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    and angular speed is linear speed/r is one formula for angular speed.

  9. anonymous
    • one year ago
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    i'm not sure how to figure out the circumference :/

  10. Curry
    • one year ago
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    angular speed = 2pi(frequency) = 2pi / (period) = linear speed / radius.

  11. Curry
    • one year ago
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    area of circle is (pi)r^2. circumference is 2pi(r).

  12. Curry
    • one year ago
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    wait, sorry, legit confused here, why are they teaching you revolutions and such without teaching how to find circumference/

  13. anonymous
    • one year ago
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    no i'm just confused about how the circumference is applied here..

  14. anonymous
    • one year ago
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    because all that is know is the radius and the 40 degrees

  15. Curry
    • one year ago
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    well, think of it like a wheel rolling. if a wheel rolls 20 times, how would you figure out how far it has rolled? Well, the way to think about it is, what if you took a belt, and made it into a circle with radius 5? now, straigten the belt. now take 20 belt lengths. that's what i'm doing here.

  16. Curry
    • one year ago
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    if a wheel rolls once, the distance it covers on the ground is 1 circumference. get it?

  17. anonymous
    • one year ago
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    oh ok :) thanks

  18. anonymous
    • one year ago
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    in terms of figuring out the angular and linear speeds how would I apply this rule?

  19. Curry
    • one year ago
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    well for linear speed, it's the same as finding speed of a car. total distance divided by total time. so 20 revoltuions divided by 60 seconds.

  20. Curry
    • one year ago
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    and if you scroll up, you'll see teh three equations i posted that you can use to find angular speed.

  21. anonymous
    • one year ago
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    oh ok thanks so much I just got confused because when I divided 20/60 I got .333 repeating and not 10.47

  22. Curry
    • one year ago
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    glad you figured it out.

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