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Jeans123 Group Title

An object is dropped from a height of 1700 ft above the ground. The function h=-16t^2+1700 gives the object’s height h in feet during free fall at t seconds. a. When will the object be at 1000ft above the ground? b. When will the object be 940ft above the ground? c. What are a reasonable domain and range for the function h?

  • 2 years ago
  • 2 years ago

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  1. cruffo Group Title
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    both part a and b are asking you to find the time t for a given h. for a, solve the following equations for t: -16t^2 + 1700 = 1000

    • 2 years ago
  2. Jeans123 Group Title
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    t=(close to) 1.654 is what I got a.

    • 2 years ago
  3. cruffo Group Title
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    I got t = 6.614 -16t^2 +1700 = 1000 -16t^2 = -700 t^2 = 43.75 then take square root of both sides

    • 2 years ago
  4. Jeans123 Group Title
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    1000=-16t^2+1700 -700=-16t^2 _/-700=_/-16t^2 26.458/16=16t/16 t=1.654 is what I did

    • 2 years ago
  5. cruffo Group Title
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    You need to divide by 16 first, before you take the square root.

    • 2 years ago
  6. Jeans123 Group Title
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    Okay got a. and b. now I just need c.:)

    • 2 years ago
  7. cruffo Group Title
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    Domain = what values of time would be used here? t > 0, since negative time not reasonable. And you probably need to find when the ball hits the ground, since after that time, the ball would be underground.

    • 2 years ago
  8. Jeans123 Group Title
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    1700=16t^2 _/-106.25=t^2 t=10.3078 Is what I got for how long it takes to hit the ground.

    • 2 years ago
  9. cruffo Group Title
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    Cool. So the a reasonable domain is from 0 to 10.3078.

    • 2 years ago
  10. cruffo Group Title
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    Range: what values of height seem reasonable? h > 0, because negative height would mean that the ball was underground. And ... since the ball was "dropped" from a height of 1700 (vs being "thrown up" from a height) the maximum height would be 1700. So ... a reasonable range would be from 0 to 1700.|dw:1352328021424:dw|

    • 2 years ago
  11. Jeans123 Group Title
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    Thank you that helped a lot! I have one more question to post can you help me with it?

    • 2 years ago
  12. cruffo Group Title
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    sure, I'll look for you.

    • 2 years ago
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