Related Rates #8 - Cars Traveling from an Intersection - Rate of Change in Perimeter

[bana]

this has been up for five years, yet it helps students everyday!
thank you!

[AnnieJoo]

up until now.. I have watched all your rate related videos!! I have more confidence than last week when I first learned it. THANK YOU PATRICKJMT!!!

[spzumz]

the speeds are given in miles per HOUR. the time given is in MINUTES. to convert 20 minutes into hours, you must divide it by 60 minutes (the amount of minutes in one hour). 20/60 = 2/6 = 1/3 (basic simplification). 20 minutes is 1/3rd of an hour, and you can now use that information in your equation.

[groundeadpackuser]

tnx patrick for ur nice explaination about Related Rates..thank you so much dude..

[dsfdotnet]

I luv these videos, feeds my closet math geek

[javiergarcia-cuervavelasco]

Hi, great explanation!

How would you resolve the problem if the intersection angle is not 90°? But you know one other angle.

Deriving the trigonometry function sin x = opposite/hypotenuse, for instance?

I'm trying to calculate the time of impact of a torpedo in a ship, where we know the the distance between me, the submarine, and the ship, and we also know the angle made from the distance between us and in its direction (angle of bow).
I know it's trigonometry, and I can calculate the angle of the torpedo, but as the ship and the torpedo got a speed I think we have to derive by time to calculate when the torpedo will impact.

[Wyzera]

What you did at around 6:40.
Is that the same as integrating the dx/dt to get 30t+C? So 30(1/3) = 10 and the C is 0 since both cars started at the intersection (0, 0)?

[jasonli]

To making things a lot easier, 2x could have been substituted into the equation before differentiating. This is because the rate of change of y is two times faster than that of x.

[kizarumelon]

but yo patrick you are one of the top teachers i use my prof even though he's teaching at a top well known university your vids are legendary patrick lol

[LeeLiFace]

instead of solving for Z, can you not use (2x+2y)/2 for the perimeter equation?

[SarahxXxMuzix]

GUYS why did he not convert minutes to hour??? I have a final and i dont know if i should just leave the minutes or convert it???

[gcharocks]

Why couldn't you just plug it in like so: dP/dt = 60 + 30 + 67? This would get you the same answer without convoluting things. *The 67 was obtained through Pythagorean's Theorem.

[RockTheOceanme]

p = 30 + 60 + sqrt (900+3600) = 157, 08

[Daftums]

Thank you. My problem was I had too little variable and did not understand how to obtain X or Y.

[afipunkluver]

I think I would've failed my calculus quiz tomorrow without you XD

[razorbladedragon]

What if the cars left at different hours?

[AnnieJoo]

BTW... can i request a shadow rate related video?

[Illmiddleaisleyouone]

P=30t+60t+((4500)^(1/2))*t and therefore rate of change of Perimeter with respect to time is dP/dt=90+sqrt4500 easy

[kizarumelon]

i'm literally watching your vids when im in my calc class lmao i have to be there for participation but im learning from you instead!

[AnnieJoo]

you convert 20 min. to 1/3 of an hour. 20 min=1/3 hour