Recent content by physjeff12

ok cool.so v'(r) = (1/3)pi(r^2)*(-1/(2*sqrt(25 - x^2)) + [(25-r^2)^(1/2)]*[(2/3)*pi*r] correct?

the sqrt(25 - x^2) represented h. x represented the radius (r in the picture). 5 represented the S on the picture. i thought the A = (1/2)theta r^2 would be irrelevant because I'm trying to find volume, not area?

V = 1/3 * pi * r^2 * h thats what i had, but i substituted in h in terms of x but using pythagorean. x^2 + h^2 = 5 ^2 h^2 = 25 - x^2 h = square root of (25 - x^2) http://z.about.com/d/math/1/5/t/L/conerr.jpg

ok, i found out the volume forumula i divided the cone into 2 right triangles, using 5 as the hypotenuse, and r as the radius of the base of the cone. so i have V = (1/3)(pi)(square root of 25 - x squared)(x squared) i am working on finding the derivative but there is so much work with the...

Homework Statement In England, you can purchase fish and chips for a reasonable price. The reason it is so reasonable is because they give you no silverware, nor a plate. They just roll up a piece of paper in a cone and toss your food in. The vendors need to roll the cone in a perfect...

4yy' = √3(y+xy') - 2x 4yy' + √3xy' = √3y - 2x (4y + √3x)y' = √3y - 2x y' = (√3y - 2x)/(4y + √3x) right?

oh i didn't know if i was doing it right. d/dx(2y2) = d/dx(5) + d/dx(√(3)xy) - d/dx(x2) 4yy' = √3(y+xy') - 2x y' = ((√3(y+xy')) - 2x)/4y

d/dx(2y2) = d/dx(5) + d/dx(√(3)xy) - d/dx(x2) 4yy' = √(3)y' - 2x y' = (√(3)y')/4y - x/2y any cigar yet?

= √3(y+xy') 4yy' = √3y + √3xy' y' = (√3y/4y) + (√3xy'/4y) y' = (√3/4) + (√3xy'/4y) closer?

oh so you can't take the derivative of 2y2, the same as your take 2x2? 4y(y') = √3(√3)y - 2x 4y(y') = 3y - 2x is that in the right direction?

thanks :smile: and how do i find the acceleration using fk? i don't know any formulas that connect acceleration with friction force. EDIT: nvm, i am stupid. i found out how. F = ma :smile:

Homework Statement find the lines that are (a)tangent and (b)normal to the curve at the given point: x2 - √(3)xy + 2y2 = 5, (√3, 2) Homework Equations dy/dx The Attempt at a Solution i am completely confused about implicit differentiation and the chain rule. I've learned...

Finding length of skid marks using fk Homework Statement A 1000kg car traveling at a speed of 40m/s skids to a halt on wet concrete where µk = 0.60. How long are the skid marks? (i know this an easy problem, but i am stuck when trying to find the length of the skid marks.) Homework...