Combination of solids
A combination of solids is a shape formed by joining two or more simple solids together.
Practice This ConceptMain explanation
Teacher explanation
Many real objects are not one single solid. They may be made from a cylinder and a hemisphere, a cone on a cylinder, or other joined parts. In such questions, the volume is found by adding the volumes of all parts, while the outer surface area includes only the exposed surfaces and excludes the joining faces.
Example
A toy may consist of a cylinder with a hemispherical top. Its total volume is the volume of the cylinder plus the volume of the hemisphere, but the circular face where they join is not counted in outer surface area.
Simple analogy
Joined solids: add volumes, hide joints.
Common confusion
Students often count hidden joining surfaces or forget to add one of the component volumes.
Exam tip
First split the object into simple solids, then add volumes or exposed areas carefully.
Answer writing and exam use
1-mark use
Write the exact meaning of combination of solids in one clean line.
2-mark use
Define combination of solids and add one example or condition.
3-mark use
Explain combination of solids, show the method or example, and mention the common mistake.
Practice this concept with focused MCQs
Open the concept quiz intro first, review the test details, and then start a focused MCQ set from this concept only. Instant score and answer review are live now.
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