How fast is the top of the ladder falling, given various distances from wall?

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mika0

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20. A young woman and her boyfriend plan to elope, but she must rescuse him from his mother, who has locked him in his room. The young woman has placeda 20-foot long ladder against his house, and is knocking on his window when his mother begins pulling the bottom of the ladder away from the house at a rate of 3 feet per second. How fast is the top of the ladder (and the young couple) falling when the bottom of the ladder is:

(a) 12 feet from the bottom of the wall?
(b) 16 feet from the bottom of the wall?
(c) 19 feet from the bottom of the wall?

help me please slve this I dont have any thougths how to do it
 
Last edited by a moderator:
mika0 said:
20. A young woman and her boyfriend plan to elope, but she must rescuse him from his mother, who has locked him in his room. The young woman has placeda 20-foot long ladder against his house, and is knocking on his window when his mother begins pulling the bottom of the ladder away from the house at a rate of 3 feet per second. How fast is the top of the ladder (and the young couple) falling when the bottom of the ladder is:

(a) 12 feet from the bottom of the wall?
(b) 16 feet from the bottom of the wall?
(c) 19 feet from the bottom of the wall?

help me please slve this I dont have any thougths how to do it
Click to expand...

If the bottom of the ladder is "B" feet away from the wall and the height of the wall where the ladder touches the wall is "H":

Can you express H in terms of B? (invoke Pythagoras)

Differentiate and continue.....
 
Last edited by a moderator:
mika0 said:
20. A young woman and her boyfriend plan to elope, but she must rescuse him from his mother, who has locked him in his room. The young woman has placeda 20-foot long ladder against his house, and is knocking on his window when his mother begins pulling the bottom of the ladder away from the house at a rate of 3 feet per second. How fast is the top of the ladder (and the young couple) falling when the bottom of the ladder is:

(a) 12 feet from the bottom of the wall?
(b) 16 feet from the bottom of the wall?
(c) 19 feet from the bottom of the wall?
Click to expand...
Draw the right triangle formed by the vertical wall, the horizontal ground, and the slanted ladder. You've labelled the triangle in the manner suggested in the previous reply (the vertical side labelled "H", the horizontal side labelled "B", and the hypotenuse labelled "20"). You've noted the provided rate of change, being dB/dt = +3. You noted that you've been asked for the value of dH/dt. You've applied the Pythagorean Theorem, and... then what?

Please be complete. Thank you! ;)
 
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