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Triangle Problem

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(@flga-2-2-2-2-2-2-2-2)
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World of Engineering (Twitter) ?????ÿ

Dec 22

?ÿ
World of Engineering Quiz:
?ÿ
A 25 ft ladder (assume it is not an extension ladder) is placed with its foot 7 ft away from a building. If the top of the ladder slips down 4 ft, how many feet will the bottom slide out?
?ÿ
 
Posted : 23/12/2020 1:06 pm
(@larry-best)
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Makes me nervous to think about it.?ÿ

 
Posted : 23/12/2020 1:13 pm
(@bill93)
Posts: 9834
 

8 ft

 
Posted : 23/12/2020 1:13 pm
(@bill93)
Posts: 9834
 
Posted by: @larry-best

Let's hope someone slid it out under control.?ÿ If it slipped because of low friction, then it's going to keep on going.

 
Posted : 23/12/2020 1:15 pm
(@mathteacher)
Posts: 2081
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Really neat problem for Pythagorean Theorem. 7, 24, and 25 make a Pythagorean Triple as do 15, 20, and 25. As the top of the ladder slides down from 24 feet to 20 feet, the bottom slides out from 7 to 15 feet.

So the answer is 8 feet.

 
Posted : 23/12/2020 1:19 pm
(@dougie)
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Posted by: @bill93

8 more ft

For a total of 15

 
Posted : 23/12/2020 1:19 pm
(@dougie)
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@mathteacher

True, as long as the ground is level and the wall is plumb

 
Posted : 23/12/2020 1:20 pm
(@ekillo)
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@bill93?ÿ I concur.

Ed

 
Posted : 23/12/2020 1:21 pm
(@mathteacher)
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The ladder violated OSHA standards when it was originally placed. Its foot should have been no more than 6.25 feet from the base of the wall and it should have extended 3 feet above the top of the wall.?ÿ

Obviously that's why it slid down the wall. It's a miracle that it stopped after 4 feet. Those engineers are going to get somebody killed.

?ÿ

 
Posted : 23/12/2020 1:28 pm
(@bill93)
Posts: 9834
 
Posted by: @dougie

There are almost always unstated assumptions required to get an answer for these math problems.?ÿ Those are the simplest assumptions to make, so lacking any other evidence we make them. Also for precise integer solutions, the 25-ft distance has to be at points of contact fixed on the ladder, and not the support a real ladder might have, e.g. a rotatable foot or rounded top end.

 
Posted : 23/12/2020 1:34 pm
(@jitterboogie)
Posts: 4275
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8.15375378312

 
Posted : 23/12/2020 1:39 pm
(@bill93)
Posts: 9834
 
Posted by: @mathteacher

it should have extended 3 feet above the top of the wall.?ÿ

I think that is only if it is used to gain access to a roof or landing.?ÿ If it is leaning against a tall wall that wouldn't apply or be possible.

 
Posted : 23/12/2020 1:46 pm
 rod
(@rod)
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Ha! Just today I worked on?ÿa safety plan involving a ladder. I had to look up the OSHA publication.

 
Posted : 23/12/2020 9:06 pm
GaryG
(@gary_g)
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Where is the guy that's supposed to be holding the ladder!!!

 
Posted : 10/01/2021 5:44 am
(@nate-the-surveyor)
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@gary_g

The guy who was supposed to be holding the ladder has Parkinson's, and was busy texting.

Another factor that's been left out is inertia, that ladder had a big fat Joe on top of it, propelling to at a rate, that made it fly!

 
Posted : 10/01/2021 9:30 am
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