Which of the following physical quantities is dimensionless __________________?
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Answer: D. strain
Explanation
Strain is calculated as a ratio comparing a change in dimension to the original dimension. Because both the numerator and denominator share identical units, the resulting value cancels out. This lack of physical dimensions makes strain a pure dimensionless numerical quantity. Dimensional analysis confirms that ratios of similar physical quantities have no associated units. Engineering strain is expressed as a simple decimal, percentage, or parts per million. Other material properties like length changes follow this same fundamental geometric principle.
Dimensionless values like strain simplify complex structural calculations across different unit systems. Finite element analysis software relies heavily on strain ratios to evaluate structural integrity. Monitoring strain helps engineers detect potential material fatigue in bridges and aircraft. Kinematic viscosity has dimensions of area divided by time, typically measured in Stokes. Surface tension represents force per unit length acting along the liquid interface. Bulk modulus possesses units of pressure, such as pascals, because it measures volumetric stress.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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