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Falling from a Tree

  • Thread starter StotleD
  • Start date
21
0
While exploring the canopy of the rainforest in equatorial South America, Anastasia falls from a branch 31.0 meters high. Exactly 1.4 seconds later Joe falls from the same branch. How high above the ground is Joe when Anastasia splats into the mud below? undefined
 
208
0
this sounds almost to easy.

y = y0 -1/2 * g* t ^2

y = 31 - 1/2 * 9.8 * (1.4) ^ 2

do the math
 
21
0
I get 21.40m (21.396 m) but the computer I am doing it on cross checks my answer and says its wrong...
 

HallsofIvy

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mathmike said:
this sounds almost to easy.

y = y0 -1/2 * g* t ^2

y = 31 - 1/2 * 9.8 * (1.4) ^ 2

do the math
Yes, it was too easy. That is Anastasia's height when Joe starts to fall. To find Joe's height when Anastasia hits the ground:

1) Solve 31- (1/2)(9.8)t2 to find time t when Anastasia hits the ground.

2) Put that value of t into h= 31- (1/2)*(9.8)(t- 1.4)2 to find Joe's height h.
 
208
0
i didnt want to do the whole problem for them, but yes halls is right
 

mukundpa

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3
For what time Joe is in motion when Anastasia splats in mud??? is it 1.4 sec ??????
 

HallsofIvy

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No, as I said before, solve (1/2)(9.8)t2- 31= 0 (her height will be 0) to find when Anastasia hits the ground.
 
21
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This is Anastasia's height. I'm trying to find Joe's...
 
88
0
StotleD said:
This is Anastasia's height. I'm trying to find Joe's...
joe's height will be
hjoe = 31 - (1/2)*(9.8)(TA - 1.4)^2
where TA is when A hits the mud found by solving
(1/2)(9.8)(TA)^2 = 31
 

DAS

1
0
StotleD: First I calculated how long it takes Anastasia to fall before hitting the ground. I came up with 2.52 seconds. If Joe falls 1.4 s after Anastasia does, and if she hits the ground after 2.52 s, then he has fallen for 1.12 s when she hits. You can calculate his distance fallen of distance above the ground or both. I got 6.15 m that Joe fell. 31.0 m - 6.15 m is the height above the ground: 24.85 m. Does that help and match your understanding and calculations?
DAS
 

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