Units Equivalent to Joules (Energy)

Steps:

• Recall joule (J) = kg·m²/s², the SI unit for energy (work, heat).
• Check A: Nm = newton·meter = (kg·m/s²)·m = kg·m²/s² = J.
• Check B: VC = volt·coulomb; 1 V = 1 J/C, so VC = J.
• Check C: Ws = watt·second; 1 W = 1 J/s, so Ws = J.
• Check D: kgms = kg·m·s, dimensions kg·m·s (momentum-like), not kg·m²/s².

Why D is correct:

• kg·m·s matches momentum (p = mv), not energy's kg·m²/s² from work formula W = F·d.

Why the others are wrong:

• A: Nm is work done by force over distance, equals J.
• B: VC is electrical potential energy, equals J.
• C: Ws is power integrated over time, equals J.

Final answer: D