horizontal strip

Area, moment of inertia, and radius of gyration of parabolic section

Situation
Given the parabola 3x2 + 40y – 4800 = 0.
 

Part 1: What is the area bounded by the parabola and the X-axis?
A. 6 200 unit2
B. 8 300 unit2
C. 5 600 unit2
D. 6 400 unit2
 

Part 2: What is the moment of inertia, about the X-axis, of the area bounded by the parabola and the X-axis?
A. 15 045 000 unit4
B. 18 362 000 unit4
C. 11 100 000 unit4
D. 21 065 000 unit4
 

Part 3: What is the radius of gyration, about the X-axis, of the area bounded by the parabola and the X-axis?
A. 57.4 units
B. 63.5 units
C. 47.5 units
D. 75.6 units
 

Example 2 | Volumes of Solids of Revolution

Example 2
Find the volume generated when the area in Example 1 will revolve about the y-axis.
 

Example 3 | Plane Areas in Rectangular Coordinates

Example 3
Find the area bounded by the curve x = y2 + 2y and the line x = 3.
 

Example 1 | Plane Areas in Rectangular Coordinates

Example 1
Find the area bounded by the curve y = 9 - x2 and the x-axis.
 

Plane Areas in Rectangular Coordinates | Applications of Integration

There are two methods for finding the area bounded by curves in rectangular coordinates. These are...

  1. by using a horizontal element (called strip) of area, and
  2. by using a vertical strip of area.

The strip is in the form of a rectangle with area equal to length × width, with width equal to the differential element. To find the total area enclosed by specified curves, it is necessary to sum up a series of rectangles defined by the strip.
 

Using Horizontal Strip

 
 
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