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Identify the correct S.I. statements: pressure, surface tension, force, and power expressed in standard units.

Difficulty: Easy

Correct Answer: All the above statements are correct.

Explanation:


Introduction / Context:
Unit literacy is essential for error-free engineering. This item cross-checks four standard S.I. expressions—pressure, surface tension, force, and power—that occur repeatedly in mechanics, fluids, and thermodynamics. Mastering them improves dimensional analysis and prevents formula misuse in longer numerical problems.


Given Data / Assumptions:

  • Pressure in S.I. is pascal (Pa) = N/m^2.
  • Surface tension is force per unit length with unit N/m.
  • Force is measured in newtons (N).
  • Power is the rate of doing work or energy transfer per unit time: watt (W) = J/s.


Concept / Approach:
Each statement can be validated by definition: pressure = normal force / area; surface tension = tangential force along a line / length; force = mass * acceleration; power = work rate = (force * velocity) = J/s. Converting each to canonical S.I. form confirms correctness without needing numbers.


Step-by-Step Solution:

Pressure: P = F/A → N/m^2, hence Pa.Surface tension: T = F/length → N/m.Force: F = m * a → measured in newtons (kg·m/s^2).Power: P = dW/dt → W = J/s = N·m/s.


Verification / Alternative check:

Dimensional check: [Pressure] = [Force]/[Area] = (M·L/T^2)/(L^2) = M/(L·T^2); [Power] = [Energy]/T = (M·L^2/T^2)/T = M·L^2/T^3.


Why Other Options Are Wrong:

Any option that excludes one of the four correct statements is incomplete, since all four expressions are standard S.I. definitions.


Common Pitfalls:

Mixing N/m (surface tension) with N/m^2 (pressure).Confusing watt (power) with newton (force) or joule (energy).


Final Answer:

All the above statements are correct.
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