Centroid Example Problem Using the Subtractive Method

The video tutorial covers problem #5 from centroid practice, focusing on the subtractive method. It explains how to calculate areas and centroids by treating certain shapes as negative areas. The tutorial walks through the steps of calculating the total area and centroids, comparing results with previous problems. The subtractive method is highlighted as a useful strategy for certain geometric problems, though the instructor prefers the additive method.

What is the main difference between the subtractive and additive methods in centroid calculation?

• Subtractive method adds areas of all shapes.

• Additive method uses negative areas for removed shapes.

• Subtractive method uses negative areas for removed shapes.

• Additive method subtracts areas of all shapes.

How is the area of the subtracted shape treated in the subtractive method?

• As a zero area.

• As a negative area.

• As a positive area.

• As a doubled area.

What is the total area of the shape after applying the subtractive method?

• 36

• 30

• 24

• 42

How is the X centroid of the first shape calculated?

• Height divided by 2.

• Height divided by base.

• Base divided by height.

• Base divided by 2.

What adjustment is made to the centroid coordinates due to the shape's position?

• Subtract the offset from the origin.

• Add the offset from the origin.

• Multiply by the offset from the origin.

• Divide by the offset from the origin.

What is the final X coordinate of the centroid after calculation?

• 3.5

• 5.0

• 4.5

• 2.7

Why might the subtractive method be preferred in some cases?

• It is always more accurate.

• It is quicker for shapes being cut out.

• It requires fewer calculations.

• It is the only method available.