Newton’s law of resistance – underlying idealizations The law assumes simplified conditions about the body and surrounding fluid. Select the statement that best captures these assumptions.

Introduction:
Newton’s law of resistance, historically used to relate drag to velocity (often leading to drag proportional to V^2 at high Reynolds numbers), relies on idealized assumptions. This question checks recognition of the classical simplifications about surface smoothness, fluid occupancy, and particle interactions.

Given Data / Assumptions:

• Classical, idealized formulation of resistance on a body moving through a fluid.
• Macroscopic viewpoint; molecular-scale interactions are not explicitly modeled.
• High-level assumptions used to derive simple resistance expressions.

Concept / Approach:
To obtain tractable expressions for drag, early formulations assume: (1) perfectly smooth body surfaces so local roughness effects on boundary layers are neglected, (2) the medium fully occupies the space (no voids), and (3) simplified interaction between fluid particles (no complex inter-particle forces beyond the continuum description). Grouping these together yields the combined alternative “all of the above.”

Step-by-Step Solution:

Verification / Alternative check:
Modern drag correlations improve on these assumptions by incorporating roughness, boundary-layer behavior, and empirical coefficients, but the foundational idealizations remain historically recognized in the simplest treatments.

Why Other Options Are Wrong:

• Individual statements (a), (b), (c) are incomplete alone; the question asks for the best capture of assumptions, which is the combined option.
• none of the above: contradicts the recognized simplifications.

Common Pitfalls:
Confusing this historical/ideal law with detailed boundary-layer theory, or assuming surface roughness and turbulence modeling are inherently included in the earliest formulations—they are not.

Final Answer:
all of the above