At noon, ship A is 50km west of ship B. Ship A is sailing south at 30km/h and ship B is sailing north at 20km/h. How fast is the distance between the ships changing at 4:00pm.

Question

anonymous · Answer

this is what i did but the answer is wrong

anonymous · Answer

|dw:1351654604093:dw|

anonymous · Answer

yes i think i got the same diagram

anonymous · Answer

yes, i agree

anonymous · Answer

did i do it a different way in the picture above?

anonymous · Answer

so the change in d is  (1/2)(50^2t)/(sqrt((50t)^2 +50^2) )

anonymous · Answer

left out a square on the 50... fixed it..

anonymous · Answer

so whats t?

anonymous · Answer

4

anonymous · Answer

let me try it 1sec

anonymous · Answer

$$\frac{ 1 }{ 2 } \frac{ 50^2t }{ \sqrt{(50t)^2 +50^2} }$$

anonymous · Answer

~24.25

anonymous · Answer

i dont think so

anonymous · Answer

i tried again and got 24.25 and its wrong

anonymous · Answer

dang... yeah, I just caught the error

anonymous · Answer

there's no 1/2 out front  because t^2 ' =2t

anonymous · Answer

$$\frac{ 50^2*t }{\sqrt{(50t)^2 +50^2 } }$$

anonymous · Answer

so 48.5

anonymous · Answer

got it. perfect, thanks

anonymous · Answer

sure:)