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 3 years ago
PLEASE HELP! PROBLEM ON RELATED RATES :)
A ball is located at point Q on top of a flagpole 10m above the ground. a light is being raised vertically at the rate of 5 m/s casting the shadow of Q on the ground. how fast is the shadow moving along the ground when the light is 50m high?
 3 years ago
PLEASE HELP! PROBLEM ON RELATED RATES :) A ball is located at point Q on top of a flagpole 10m above the ground. a light is being raised vertically at the rate of 5 m/s casting the shadow of Q on the ground. how fast is the shadow moving along the ground when the light is 50m high?

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beens
 3 years ago
Best ResponseYou've already chosen the best response.0where is the light initially?

helllo
 3 years ago
Best ResponseYou've already chosen the best response.020 meters from the flagpole! coming from the top

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0dL/dt = 5 ....dh/dt = 0 dx/dt =? dx/dt = dx/dL * dx/dt find dx/dL ?? maybe not tho.....

beens
 3 years ago
Best ResponseYou've already chosen the best response.0is there an initial height of the light?

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0ahhh...... the shadow moving problem in all the textbooks :)

rejanae13
 3 years ago
Best ResponseYou've already chosen the best response.0well you need to cross multiply and divide. so it would be 20m/50m by 5m/x.... that would be 50x by 100... divide 50 by 100 to get x alone and you get x=2

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0thats a rough drawing by the way :)

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0h/(20+x) = 10/(x) if that helps :)

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0lol sorry thats what was given to me :p

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0dx/dt = x^2(dy/dt)/200 ?? maybe

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0im gonna take a gander and say... 25(5) = 125 125/200 = ?? .0625 ?? if I did it right lol

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0i think I got the "equation" wrong at the start....

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0lol thank you! ..but i dont understand how can you have dy/dy? :s

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0lol so the whole thing is wrong??

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0:) fat fingers...little tiny keyboard :)

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0it may be right, but I dont trust it yet.... need to find the equation to derive; then the rest is easy.

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0ya but thats the part i cant get! wahh :(

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0I am thinking it is the relation of congruent triangles; "y" being the height of the lamp: x = length of shadow. 10/x = y/(20+x) is what I come up with; there is no question about the distance of the light to the tip of the shadow...

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.010(20+x) = y(x) (200+10x)/x = y 200/x + 10 = y 200/x = y10 200/(y10) = x ??? sounds good

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0this relate y and x..... now implicit it with respect to time right?

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0yea thats what i gotta do

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0and thank youuu! for everything so far btw!

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0200(dy/dt) / (y10)^2 = dx/dt dy/dt = 5 y = 50;

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0no prob; I live to math things up lol

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.00.625 is what i get, and I am almost sure its right... but i get that nagging feeling that I am just being stupid :)

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0hahaha but where did u get negative two hundred?

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0ok.... step it out.... 200 x =  (y10) (y10)(0)  (200)(dy/dt) dx/dt =  (y10)^2

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0lol im on the phone with my friend trying to figure this out and im reading her what u wrote and we both agreed your funny, just thought id let you know :p but yea we dont understand also where you got the 50 from? (: care to explain?

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0200(dy/dt) dx/dt =  (y10)^2

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0when y=50...its right there :)

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0dy/dt is given already as the rate of change in "y"... = 5 m/s

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0as y rises; x shrinks.... so its () direction..

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0ohhh okay! thank you so so much honestly, it means a lot (: (:

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0just let me know if im right :)

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0i will haha but its the first time im on this site so how can i tell you?

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0because i have to check with my teacher first

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0shout really loud? :) AMISTRE WAS RIGHT!!!.... or if im wrong it would be: AMISTRE WAS WRONG .... ill feel it either way :)

amistre64
 3 years ago
Best ResponseYou've already chosen the best response.0that moving shadow thing is in all the calc textbooks If seen, and it always makes me nervous

helllo
 3 years ago
Best ResponseYou've already chosen the best response.0lol im sure you got it right though, it seemed to make sense. i found it impossible!
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