Question

Ben and Josh went to the roof of their 40-foot tall high school to throw their math books off the edge.

Answer 1

Answer:

• Josh's book lands first
• Ben's lands about 0.648 seconds later

Step-by-step explanation:

Using the given equation for v=60 and s=40, the height of Ben's book is ...

  h(t) = -16t² +60t +40

We want to find t when h(t) = 0, so we're looking for the solution to ....

  0 = -16t² +60t +40

Using the quadratic formula, we find the positive value of t to be ...

  t = (-60 -√(60² -4(-16)(40)))/(2(-16)) = (15 +√385)/8 ≈ 4.3277

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Similarly, the height of Josh's book is ...

  0 = -16t² +48t +40

  t = (-48 -√(48² -4(-16)(40)))/(2(-16)) = (12 +√304)/8 ≈ 3.6794

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The time before Josh's book lands is shorter by ...

  4.3277 -3.6794 ≈ 0.6482 . . . . . seconds

Josh's book reaches the ground first, by about 0.648 seconds.