Volume of Solid w/ Semicircular Cross Sections in 1st Quadrant

In summary, the base of the solid is a region bounded by the x-axis, y-axis, and the line x+2y=8 in the 1st quadrant. The cross sections of the solid perpendicular to the x-axis are semicircles. The volume of the solid can be found by integrating from 0 to 8 the function 1/2pi(4-x/2)^2. The correct answer is choice c, 16.755.
  • #1
radtad
19
0
The base od a solid is a region in the 1st quadrant bounded by the x-axis, y-axis and the line x+2y=8. If cross sections of the solidperpendicular to the x-axis are semicircles, what is the volume of the solid?

How come the answer isn't just the intgegral from 0-8 of 1/2pi(4-x/2)^2
 
Physics news on Phys.org
  • #2
radtad said:
The base od a solid is a region in the 1st quadrant bounded by the x-axis, y-axis and the line x+2y=8. If cross sections of the solidperpendicular to the x-axis are semicircles, what is the volume of the solid?

How come the answer isn't just the intgegral from 0-8 of 1/2pi(4-x/2)^2

That's what it looks like to me. Is it the wrong answer?
 
  • #3
yea according to the answer key its wrong
 
  • #4
choices are
a. 12.566 b. 14.661 c. 16.755 d 67.021 e 134.041

i keep ending up with choice d but the answer key says its choice c
 
  • #5
Oh I see now. I misunderstood the problem. I did it by finding the solid after rotating about the x-axis and integrating... But the cross section of this solid is the circle whose diameter is from y=0 to y=4-x/2. We were thinking the cross section was a circle with diameter from y=-(4-x/2) to y=4-x/2. But if we make the radius (4-x/2)/2, then we get the right answer.

0-8 of 1/2pi[1/2(4-x/2)]^2 is correct.
 
  • #6
yea i realized that too thanks
 

Related to Volume of Solid w/ Semicircular Cross Sections in 1st Quadrant

What is the formula for finding the volume of a solid with semicircular cross sections in the 1st quadrant?

The formula for finding the volume of a solid with semicircular cross sections in the 1st quadrant is V = πr^2h, where r is the radius of the semicircle and h is the height of the solid.

How do you determine the radius and height of a semicircular cross section in the 1st quadrant?

The radius of the semicircle can be determined by finding the distance from the center of the semicircle to the edge. The height of the solid can be determined by finding the difference between the highest point of the semicircle and the x-axis.

Can the volume of a solid with semicircular cross sections in the 1st quadrant be negative?

No, the volume of a solid cannot be negative as it represents the amount of space occupied by the solid. If the radius or height values used in the formula result in a negative number, it means the solid does not exist.

How is the volume of a solid with semicircular cross sections in the 1st quadrant affected by changing the radius and height?

As the radius and height values are directly proportional to the volume, increasing or decreasing these values will result in a corresponding increase or decrease in the volume of the solid. This is because a larger radius or height will result in a larger semicircular cross section, leading to a larger volume.

Is there a limit to the number of semicircular cross sections that can be used to find the volume of a solid in the 1st quadrant?

No, there is no limit to the number of semicircular cross sections that can be used to find the volume of a solid in the 1st quadrant. The more cross sections that are used, the more accurate the volume calculation will be.

Similar threads

Replies
2
Views
1K
Replies
6
Views
1K
  • Calculus and Beyond Homework Help
Replies
4
Views
957
  • Calculus and Beyond Homework Help
Replies
3
Views
977
  • Calculus
Replies
3
Views
1K
Replies
4
Views
410
  • Calculus and Beyond Homework Help
Replies
1
Views
923
  • Introductory Physics Homework Help
Replies
4
Views
13K
  • Calculus and Beyond Homework Help
Replies
8
Views
3K
  • Calculus and Beyond Homework Help
Replies
3
Views
2K
Back
Top