Question

The function y = -16x2 + 1500 gives a parachute jumper's height y in feet

after "X" seconds for a jump from 1500 feet. How long is free fall if the
parachute opens at 1100 feet?

Answer 1

Explanation:

so the question is asking about the time from 1500 feet to 1100 feet. How long did they fall, w/o a parachute. aka "freefall" so, at 1500 feet the jumper is really at time zero. so, plug in to the formula

1100 = -16
`x^(2)` +1500

( x represents seconds so i'll change it to t so we know it's time )

1100 = -16
`t^(2)` + 1500

now we can solve for t , to see how long the jumper falls

-400 = - 16
`t^(2)` ( subtracting 1500 from both sides of equation )

25 =
`t^(2)` ( dividing both sides by -16 )

oh.. look at how nice that turns out.. :)

`√(25)` = t ( take the square root on both sides )

5 = t

the jumper fell for 5 seconds to get to 1100 feet