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greentravis

  • one year ago

Margy is trying to improve her cardio endurance by performing an exercise in which she alternates walking and running 100.0 m each. If Margy is walking at 1.4 m/s and accelerates at 0.20 m/s2 during one of the running portions, what is her final velocity at the end of the 100.0 m? Round your answer to the nearest tenth.

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  1. dan815
    • one year ago
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    okay so

  2. dan815
    • one year ago
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    she starts at 1.4 m/s and accelerates 0.2 m/s^2 over a distance of 100.0m

  3. dan815
    • one year ago
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    now okay lets suppose it takes t seconds for her to run this 100.0m while she is accelerating

  4. dan815
    • one year ago
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    now the velocity over this time period will look like v(t) = 1.4 + 0.2 *t <---- tells you the veloicty with respect to the time the distance over this time will look like the area under this graph, as that will tell you how much distance is constantly being covered over this time, now the area has to be = 100 in total, so wee see the time that takes and the final velocity

  5. greentravis
    • one year ago
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    okay

  6. dan815
    • one year ago
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    |dw:1444179878145:dw|

  7. dan815
    • one year ago
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    |dw:1444179933274:dw|

  8. dan815
    • one year ago
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    this is a trapezoid which can be broken down into a triangle and a rectangle, what is the area of this?

  9. dan815
    • one year ago
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    or u can take the average height of this traepezoid and multiply by the width thats the same thing

  10. dan815
    • one year ago
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    |dw:1444180009855:dw|

  11. greentravis
    • one year ago
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    so the area would be 6.5 m/s right?

  12. dan815
    • one year ago
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    no the area is 100 m the area is the distance since this is veloicty vs time graph and veloicty * time = displacements or i guess distance here

  13. greentravis
    • one year ago
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    okay

  14. dan815
    • one year ago
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    this method is probably new to u... just ask me anything u want

  15. dan815
    • one year ago
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    theres also jut a formula u can use, maybe that better for just now

  16. dan815
    • one year ago
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    x(t) = Xi+Vi*t + 1/2at^2 Xi is the initial position taken to be 0 here Vi is initial speed which is 1.4 m/s a is 0.2 m/s^2 and you know total distance was 100 so 100= 0+1.4*t + 1/2 * 0.2 * t^2 solve for t and then use the fact that v=1.4+0.2*t, to find the final velocity

  17. greentravis
    • one year ago
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    i mean velocity

  18. dan815
    • one year ago
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    velocity or speed same thing here, because this is one just 1 dimension and hes only moving forward so

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