Limitations Of Dimensional Analysis

NCERT Class 11, Chapter 2 (Units and Measurements) cautions that dimensional analysis has clear limitations, chief among them the inability to determine dimensionless quantities. Pure numbers such as one half or two pi, and dimensionless functions such as sine, cosine or exponential, carry no dimensions, so the method cannot fix their values or verify their presence. This is exactly why an equation containing a trigonometric function cannot be fully validated by dimensions alone. The option that it cannot check force is wrong because force has well defined dimensions and is readily checked. The option that it cannot apply to mechanical quantities is wrong as mechanics is the primary domain of dimensional analysis. The option that it always gives the exact coefficient is wrong since the method explicitly cannot find numerical constants. A final check confirms that the strength of dimensional analysis lies in testing consistency, not in supplying dimensionless factors, which aligns with the chosen limitation.