# Finding Volumes Using the Disk Method

#### Posted February 25, 2014

#### by Lensyl Urbano

This VPython program was written by a student, Mr. Alex Shine, to demonstrate how to find the volume of a curve that’s rotated around the x-axis using the disk method in Calculus II.

The program finds volume for the curve:

between *x = 0* and *x = 3*.

To change the curve, change the function *R(x)*, and to set the upper and lower bounds change *a* and *b* respectively.

*volume_disk_method.py* by Alex Shine.

from visual import* def R(x): y = -(1.0/4.0)*x**2 + 4 return y dx = 0.5 a = 0.0 b = 3.0 x_axis = curve(pos=[(-10,0,0),(10,0,0)]) y_axis = curve(pos=[(0,-10,0),(0,10,0)]) z_axis = curve(pos=[(0,0,-10),(0,0,10)]) line = curve(x=arange(0,3,.1)) line.color=color.cyan line.radius = .1 line.y = -(1.0/4.0) * (line.x**2) + 4 #scene.background = color.white for i in range(-10, 11): curve(pos=[(-0.5,i),(0.5,i)]) curve(pos=[(i,-0.5),(i,0.5)]) VT = 0 for x in arange(a + dx,b + dx,dx): V = pi * R(x)**2 * dx disk = cylinder(pos=(x,0,0),radius=R(x),axis=(-dx,0,0), color = color.yellow) VT = V + VT print V print "Volume =", VT

**Citing this post**: **Urbano**, L., 2014. Finding Volumes Using the Disk Method, Retrieved July 23rd, 2017, from *Montessori Muddle*: http://MontessoriMuddle.org/ .**Attribution (Curator's Code )**: Via: ᔥ Montessori Muddle; Hat tip: ↬ Montessori Muddle.