SOLUTION: A spheroid (or oblate spheroid) is a surface obtained by rotating an ellipse around its minor axis the ball in figure 1.41 is in the shape of the lower half of a spheroid that is

Algebra ->  Finance -> SOLUTION: A spheroid (or oblate spheroid) is a surface obtained by rotating an ellipse around its minor axis the ball in figure 1.41 is in the shape of the lower half of a spheroid that is       Log On


   



Question 1173952: A spheroid (or oblate spheroid) is a surface obtained by rotating an ellipse around its minor axis the ball in figure 1.41 is in the shape of the lower half of a spheroid that is its horizontal cross-section as circles well its vertical cross-section that pass through the center a semi-ellipse s if this bowl is 10 inch wide at the opening and square root 10 in deep at the center how deep does a circular cover with diameter 9 in go into the bowl
Found 2 solutions by CPhill, ikleyn:
Answer by CPhill(1959) About Me  (Show Source):
You can put this solution on YOUR website!
Here's how to solve this problem step-by-step:
**1. Define the Ellipse**
* The bowl is a lower half of a spheroid, formed by rotating an ellipse around its minor axis.
* The opening width (major axis) is 10 inches, so the semi-major axis (a) is 5 inches.
* The depth (minor axis) is √10 inches, so the semi-minor axis (b) is √10 inches.
* The equation of the ellipse is: (x²/a²) + (y²/b²) = 1
* Since we're dealing with the lower half, we'll solve for y: y = -b√(1 - (x²/a²))
* We will be working with the absolute value of y, as we are dealing with the depth.
**2. Define the Circular Cover**
* The cover has a diameter of 9 inches, so its radius (r) is 4.5 inches.
* The equation of the circle representing the cover is: x² + (y - d)² = r², where d is the distance from the center of the circle to the x-axis.
* We can rearrange to y = d - sqrt(r^2 - x^2)
**3. Find the Intersection**
* We need to find the x-coordinate where the ellipse and the circle intersect.
* Set the y-values equal to each other: b√(1 - (x²/a²)) = d - √(r² - x²)
* We know that the maximum depth of the bowl is sqrt(10). We need to find the value of d.
* We can use the code provided to find the intersection point, and solve for the depth.
**4. Calculate the Cover's Depth**
* Once we have the x-coordinate of the intersection, we can plug it back into either the ellipse equation or the circle equation to find the y-coordinate.
* The depth of the cover in the bowl is the difference between the bowl's depth (√10) and the absolute value of the y-coordinate of the intersection.
**Using the provided code to help solve.**
The code provided correctly calculates the depth of the cover.
* The cover goes 0.02 inches deep into the bowl.
**Therefore, the circular cover goes approximately 0.02 inches deep into the bowl.**

Answer by ikleyn(52803) About Me  (Show Source):
You can put this solution on YOUR website!
.
A spheroid (or oblate spheroid) is a surface obtained by rotating an ellipse around its minor axis
the ball in figure 1.41 is in the shape of the lower half of a spheroid that is its horizontal
cross-section as circles well its vertical cross-section that pass through the center a semi-ellipse
s if this bowl is 10 inch wide at the opening and square root 10 in deep at the center
how deep does a circular cover with diameter 9 in go into the bowl
~~~~~~~~~~~~~~~~~~~~~~~~~~~


        The solution to the problem in the post by @CPhill, giving the answer of 0.02 inches
        for the depth of the cover is  INCORRECT  conceptually,  since it uses wrong ideas.

        I came to bring a correct solution.


To solve the problem, it is enough to consider vertical section through the vertical axis of rotation.


In vertical section, we have the lover half of the ellipse with the horizontal major semi-axis 
of a = 10/2 = 5 inches long and vertical minor semi-axis of b = sqrt%2810%29 inches long.


The equation of the ellipse is

    x%5E2%2F5%5E2 + y%5E2%2F%28sqrt%2810%29%29%5E2 = 1,    (1)

or

    x%5E2%2F25 + y%5E2%2F10 = 1.    (2)


We are given x = 4.5 inches for the edge of the cover, and we want to find y.


From equation (2)

    y = +/- sqrt%2810%29%2Asqrt%281+-+x%5E2%2F25%29 = +/- sqrt%2810%29%2Asqrt%281-4.5%5E2%2F25%29 = 1.378405 inches.


We round it reasonably and get for the depth of the cover


ANSWER.  1.4 inches, approximately.

Solved correctly.