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A smoke jumper jumps from a plane at 1700 feet above ground. The function y=-16t^2+1700 gives the jumper's he

A smoke jumper jumps from a plane at 1700 feet above ground. The function y=-16t^2+1700 gives the jumper's height y in feet at t seconds.

How long is the jumper in free fall if the parachute opens at 1000 feet? What about at 940 feet???

please help

7 Answers

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  • E
    Lv 5
    1 decade ago
    Favorite Answer

    just substitute the height the shute opens at for y and then solve for t to get the time.

    1000 = -16t^2 + 1700

    t = sqrt(43.75)

    940 = -16t^2 + 1700

    t = sqrt(47.5)

  • 1 decade ago

    y = -16t²+1700

    For height 1000 metes:

    1000 = -16t²+1700

    1000 + 16t² = +1700

    16t² = +1700 - 1000

    16t² = 700

    t² = 700 /16

    t² = √[700 /16]

    t = 6∙614 378......

    t ≈ 6∙61 sec.

    y = -16t²+1700

    For height 940 metes:

    940 = -16t²+1700

    940 + 16t² = +1700

    16t² = +1700 - 940

    16t² = 760

    t² = 760 /16

    t² = √[700 /16]

    t = 47∙5

    t ≈ 6∙892 02....

    t ≈ 6∙89 sec.

  • 1 decade ago

    The function for the time in freefall is: y=-16t^2+1700

    In the two situations, the height (y) will be equal to 940, and a 1000.

    Plug in the values for y:

    1000=-16t^2+1700

    -700=-16t^2

    -175/4=-t^2

    t^2=175/4

    t= sqr (175)/2

    t=5 sqr 7/2, or 2.5 sqr. 7

    The next value: 940

    940=-16t^2+1700

    -760=-16t^2

    t^2=760/16

    t=2 sqr.(190)/4

    t=0.5 sqr. (190)

  • 1 decade ago

    The equation for free fall

    y=-16t^2+1700

    1] y=1000

    1000=-16t^2+1700

    t^2=700/16

    T=6.6143sec

    2]y=940

    similarly

    t^2=760/16

    t=6.89sec

  • 1 decade ago

    If the parachute opens at 1000 feet, he is in free-fall for 6.61 seconds. If it opens at 940 feet, he is in free-fall for 6.89 seconds.

    it's very simple algebra, just plug in 1000 or 940 for y, then solve the given equation for t.

  • 1 decade ago

    y=-16t^2+1700

    y1=1700, t1=0

    y2=1000, t2=?

    1000=-16(t2)^2+1700

    (t2)^2 = (1000-1700)/(-16)

    t2 = SQRT(43.75) = 6.61 seconds

    Repeat with y3=940

  • Anonymous
    1 decade ago

    6.6 seconds and 6.9 seconds, respectively.

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