Calculus I · Unit 3B · review
Unit 3B Review: Applications of Integration
Review Unit 3B Review: Applications of Integration with a structured summary, common-error repair, mixed practice, and links back to the relevant BetterGrades.
Section overview
Review, practice, exams, and answer keysWhat this section is building
Review Unit 3B Review: Applications of Integration with a structured summary, common-error repair, mixed practice, and links back to the relevant BetterGrades.
A complete solution connects context, variable, bounds, slice contribution, integral, computation, units, interpretation, and a reasonableness check.
Classify the output and geometry first, solve from a blank start, then reveal one worked answer only to diagnose the earliest divergent decision.
Reading a key before forming a setup or treating every wrong result as algebra when the real error was a radius, width, density, or bound.
Unit 3B Review
Modeling questions to ask
• What small object or contribution am I adding? • What variable naturally locates that object? • What is its size, density, force, or distance factor? • What are the correct bounds? • Do the units of the integrand times the differential produce the desired units? • Does the sign have physical or geometric meaning?
Find the area between and on using vertical slices.
Exercise 1 answer
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Set up and evaluate the same area between and using horizontal slices.
Exercise 2 answer
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For the region between and on , find the volume about the -axis with washers and the volume about the -axis with shells. Compare how radius and height are defined.
Exercise 3 answer
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The base is the region under above the -axis for . Cross-sections perpendicular to the -axis are semicircles whose diameters lie in the base. Find the volume.
Exercise 4 answer
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Find the arc length of on , then verify the result with the distance formula between the endpoints.
Exercise 5 answer
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A rod occupies and has density . Find its mass and center of mass.
Exercise 6 answer
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A spring has constant . Find the work required to stretch it from to beyond equilibrium.
Exercise 7 answer
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A full conical tank is high with top radius . Water is pumped to an outlet above the top. Set up and evaluate the work using .
Exercise 8 answer
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A vertical rectangular plate is wide and extends from the water surface to a depth of . Find the hydrostatic force using .
Exercise 9 answer
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Marginal cost is dollars per unit and . Find and identify the accumulated added cost.
Exercise 10 answer
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