All Calculus 1 Resources
Example Questions
Example Question #3931 : Calculus
Find the volume generated by rotating the region between and around the -axis.
Since the functions are being rotated around the y-axis, they should be rewritten. It may help to write them in terms of y:
And
Here, function designations have been used solely to eliminate the ambiguity of using x for both functions.
Now, there are two points of intersection for these functions:
These will be the bounds for the integration to follow.
Finally, treat these two functions as the radii for two regions: a disk from the larger radius, and a hole from the smaller radius, allowing for the formation of a ring with a cross-sectional area:
These disks have infinitesimal thickness , and so the volume of the solid can be found by adding all of these disks together; i.e. by taking the integral:
Example Question #3931 : Calculus
Find the volume of the function
revolved around the -axis on the interval .
cubic units
cubic units
cubic units
cubic units
cubic units
The formula for the volume of the region revolved around the x-axis on the interval is given as
where .
As such,
.
When taking the integral, we will use the inverse power rule which states,
.
Applying this rule we get
.
And by the corollary of the First Fundamental Theorem of Calculus
.
As such, the volume is
cubic units.
Example Question #3932 : Calculus
Find the volume of the function revolved around the -axis on the interval .
cubic units
cubic units
cubic units
cubic units
cubic units
The formula for the volume of the region revolved around the x-axis on the interval is given as
where .
As such,
.
And by the corollary of the First Fundamental Theorem of Calculus
.
As such, the volume is
cubic units.
Example Question #21 : Regions
Find the volume generated by rotating the function around the -axis over the interval .
To approach this problem, treat the function as the radius of a disc, with infintesimal thickness dx (which has the x-axis going through its center).
This infinitesismal volume of this disc is:
Now the volume of the solid rotated around the x-axis is the sum of these discs. In other word, it is the integral:
Note that the derivative of is , so from this we can infer that the integral of is :
Example Question #3931 : Calculus
Find the volume of the solid generated by rotating the parabola around the -axis, over the region where the function is greater than or equal to zero.
In stating the bounds, the question is asking that we use those values of x where the function intercepts the x-axis:
Now, treat the function as the radius of a disc with infinitesimal thickness . The volume of this disc is thus
And the volume can found via integration:
Example Question #3934 : Calculus
For this problem assume that volume is given by:
, where is the surface area function.
Given the formula for surface area of a structure is given by .
Determine the volume function of this structure.
For this problem assume that is not a function of . given below is a constant.
We're given that
Since the indefinite integral is with respect to , we can move the surface area function in front of the integral since we are told that is not a function of .
Using the power rule,
, where is a constant.
In our problem
Therefore, volume can be given as
Example Question #2908 : Functions
Using the method of cylindrical disks, find the volume of the region of the graph of the function
on the interval .
units cubed
units cubed
units cubed
units cubed
units cubed
The formula for volume is given as
where .
As such,
.
When taking the integral, we will use the inverse power rule which states
.
Applying this rule term by term we get
And by the corollary of the first Fundamental Theorem of Calculus,
As such, the volume is
units cubed.
Example Question #2909 : Functions
Using the method of cylindrical disks, find the volume of the region of the graph of the function
on the interval .
units cubed
units cubed
units cubed
units cubed
units cubed
The formula for volume is given as
where .
As such,
.
When taking the integral, we will use the inverse power rule which states
.
Applying this rule term by term we get
.
And by the corollary of the first Fundamental Theorem of Calculus,
.
As such, the volume is
units cubed.
Example Question #2910 : Functions
Set up the integral to find the volume of the solid if the region is bounded by and , revolved about .
For this problem, we will use the shell method. Write the formula for the shell method.
The thickness of the shell is .
The radius of the shell is the distance from the y-axis to the vertical rectangles, .
The height of the shell is the top curve subtract the bottom curve. The top curve is and the bottom curve is . The height is: .
Determine the bounds by setting the top and bottom equations equal to each other.
Solve for roots.
The roots are and will be the bounds to the integral. Write the integral.
Example Question #3935 : Calculus
A sphere with a radius of 5 has a segment with perpendicular planes cut out of it, such as is pictured above.
If the first cut is 4 units to the left of the origin and the second cut is 2 units to the left of the origin, what is the volume of the segment?
To approach this problem, begin by picturing how the sphere might be projected onto the two-dimensional Cartesian plane:
In its two-dimensional projection, we notice the outline of a circle. The formula for a circle of radius in the Cartesian coordinate system is given as:
Which can be rewritten in terms of as
Now note the disk method of volume creation wherein we rotate a function around an axis (for instance, the x-axis):
The new function in the integral is akin to the formula of the volume of a cylinder:
where and
The integral sums up these thin cylinders to give the volume of the shape.
Treating as our , this integral can be written as:
Consider the points where circle contacts the x-axis, the greatest and smallest possible values of on the circle:
This is how the volume of a sphere can be derived, and similary, this is how we can derive the area of our segment: