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Question

A 10m ladder is leaning against the vertical wall of a house. If the lower end of the ladder is being pulled horizontally away from the wall at the rate of 0.6m/s, how fast is the top of the ladder sliding down the wall when the lower end is 8m away from the wall? 

 

 

I just need to know if my answer is right. I ended up getting -0.8m/s

Answer 1

x^2 + y^2 =100

 

2x(x') + 2y(y') = 0

 

we are solving for y'

 

y ' = -x(x ')/y

 

We are given x ' = .6

 

We are given x = 8

 

We need to find y

 

we have x^2 + y^2 = 100

 

Therefore when x = 8, y = 6

 

So, y ' = -8(.6)/6

 

y ' = -.8 

 

sliding down at .8 m/s