SOLUTION: Ella throws a hockey puck up at a rate of 20 ft/sec from a height of 5 feet.
How long will it take for the hockey puck to hit her on the head if Ella is 5.5 ft tall?
I solved
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-> SOLUTION: Ella throws a hockey puck up at a rate of 20 ft/sec from a height of 5 feet.
How long will it take for the hockey puck to hit her on the head if Ella is 5.5 ft tall?
I solved
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Question 1181274: Ella throws a hockey puck up at a rate of 20 ft/sec from a height of 5 feet.
How long will it take for the hockey puck to hit her on the head if Ella is 5.5 ft tall?
I solved it and got 0.026 and 1.23 as the answers (rounded), but I don't know which one is the correct answer.
Also I used the equation . a is 32. Answer by ikleyn(52788) (Show Source):
You can put this solution on YOUR website! .
Ella throws a hockey puck up at a rate of 20 ft/sec from a height of 5 feet.
How long will it take for the hockey puck to hit her on the head if Ella is 5.5 ft tall?
I solved it and got 0.026 and 1.23 as the answers (rounded), but I don't know which one is the correct answer.
Also I used the equation h=-0.5a^2 + vt + s. a is 32.
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The equation you used looks strange.
The standard and canonical equation to be used in such problems, is h = -0.5a*t^2 + vt + s with a = 32 m/s^2.
With the numbers, the equation to find the flight time (= "how long will it take") is
-16t^2 + 20t + 5 = 5.5,
or
16t^2 - 20t + 0.5 = 0
for simplicity.
Its solution is
= = = .
Of the two roots, you select the greater one (because the smaller time is for ASCENDING BRANCH)
t = = 1.225 seconds.
ANSWER. It will take 1.225 seconds to hit her on the head.
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