NCERT Solutions for Class 8 Science Chapter 12
Important NCERT Questions
8th Chapter 12 Friction
NCERT Books for Session 2022-2023
CBSE Board and State Board
Questions No: 10
Explain why objects moving in fluids must have special shapes.
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The frictional force exerted by fluids is also called drag or fluid friction. To overcome or minimize air fluid friction, the bodies of objects minimise its surface i.e. sometime spherical shapes or other streamlined shape with smooth surface. Aeroplanes, jets, rain drops have streamlined curve surface to reduce air drag.
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Objects moving through fluids encounter resistance known as drag. Specialized shapes are crucial to minimize this drag by altering fluid flow around the object. This adaptation is based on two fundamental principles:
1. Streamlined Shape: Utilizing streamlined or aerodynamic shapes reduces resistance. These shapes allow fluids to flow smoothly around the object, minimizing turbulent flow and reducing drag. Examples include streamlined airplane wings, car designs, and the sleek forms of fish.
2. Pressure Drag Reduction: Some shapes aim to diminish pressure drag, arising from pressure differences on the object’s surfaces. A teardrop shape, for instance, reduces pressure drag by gradually tapering at the rear, lessening pressure discrepancies between the object’s front and rear.
Special shapes for objects moving in fluids aim to optimize efficiency by promoting smoother fluid flow and minimizing pressure differences, consequently reducing energy consumption during movement.