A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Find the time intervals for v(t) = t^2 - 9t + 18 when the particle is a.going faster b.slowing down

  • This Question is Closed
  1. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so iv go a. (4.5 , infinity) b. (-infinity , 4.5) but apparently their is 2 intervals for each

  2. ganeshie8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    see if the graph helps |dw:1438632617992:dw|

  3. ganeshie8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    I think you also need to look at the points where the velocity is becoming 0 (x intercepts)

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes thats what i was thinking but that wouldn't allow 2 intervals for each

  5. ganeshie8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1438633001610:dw|

  6. Astrophysics
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    You could use acceleration to your advantage just look at where the acceleration is increasing, and then you can use similar way to determine where it's decreasing as the sign will be opposite of the velocity.

  7. Astrophysics
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    But ganeshies graph is perfect to, as you can tell easily with it xD

  8. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yeah i used the acceleration graph to find my answer initially, to be honest i still don't know why its wrong

  9. ganeshie8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    From the graph it is clear that the particle's "speed" is decreasing in the interval \((-\infty, ~3)\). Then the particle has changed its direction, and its "speed" starts increasing in the interval \((3,~4.5)\). After that, the particle slows down, its "speed" starts decreasing in the interval \((4.5, ~6)\) and becomes \(0\) at \(t=6\). For the rest, the speed keeps increasing.

  10. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    speed=|velocity||dw:1438633412827:dw| you could reflect the part that is below the graph about the x-axis

  11. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    below the graph I mean below the x-axis

  12. ganeshie8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    That speed graph looks so much clear!

  13. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    okay so then it would be a.(3,4.5)U(6,infinity) b.(-infinity,3)U(3,6)

  14. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    is that right?

  15. Astrophysics
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Mhm

  16. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    well

  17. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    there is one endpoint just a tad off

  18. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    where are you getting the eight from ?

  19. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    \[\text{ "okay so then it would be } \\ a.(3,4.5) \cup (6,\infty) \\ b.(-\infty,3) \cup (\color{red}{3},6) \\ \text{ " } \\ \text{ I think this 3 is a type-o}\]

  20. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    yes it is i ment (4.5 , 6)

  21. freckles
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    cool stuff then

  22. ganeshie8
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 3

    |dw:1438633971759:dw|