SOLUTION: Hi, could you perhaps shed some light on this problem? "Sky divers are in free fall from the time they jump out of a plane until they open their parachutes. A sky diver jumps from

Question 711321: Hi, could you perhaps shed some light on this problem? "Sky divers are in free fall from the time they jump out of a plane until they open their parachutes. A sky diver jumps from 5000 feet. The diver's height 'h' above the ground 't' seconds after the jump is described by the equation 'h=-16t^2 (squared)+ 5000.' Find the time during which the diver is in free fall assuming that the parachute opens at 1000 feet." Where did the -16t^2 come from? and where does the 1000ft distance come in? Any help would be greatly appreciated!

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Sky divers are in free fall from the time they jump out of a plane until they open their parachutes.
A sky diver jumps from 5000 feet.
The diver's height 'h' above the ground 't' seconds after the jump is described by the equation 'h=-16t^2 (squared)+ 5000.'
Find the time during which the diver is in free fall assuming that the parachute opens at 1000 feet."
;

-16t^2 represents the average downward attraction to the earth by gravity
:
You start at 5000 ft, you want the free fall to end at 1000 ft (parachute opens)
therefore h(t) = 1000, find how many seconds for this to happen
:
-16t^2 + 5000 = 1000
subtract 5000 from both sides
-16t^2 = 1000 - 5000
-16t^2 = -4000
t has to be positive, multiply both sides by -1
16t^2 = 4000
divide both sides by 16
t^2 = 250
find the square root of both sides
t =
t = 15.811 seconds to fall to 1000 ft
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