Which of the following are the correct S.I units of the quantities indicated? (i) Torque (Nm) (ii) m

JAMB Physics 2023 55 views

Which of the following are the correct S.I units of the quantities indicated? (i) Torque (Nm) (ii) momentum (kgms-2) (iii) Power (Watt/s) (iv) Pressure (kgm-1s-2)

Which of the following are the correct S.I units of the quantities indicated? (i) Torque (Nm) (ii) momentum (kgms-2) (iii) Power (Watt/s) (iv) Pressure (kgm-1s-2)

  1. (i), (iii) and (iv)
  2. (i) and (iv) only ✓
  3. (i), (ii) and (iii) only
  4. (i) and (iii) only

Explanation

AC voltage follows sine wave: V = V₀sin(2πft) where V₀ is peak voltage. Frequency f = 50 Hz in Nigeria (50 cycles per second, period 0.02 s).

RMS (root mean square) values are DC equivalents: V_rms = V₀/√2 ≈ 0.707 × V₀. Nigerian mains is 220V RMS, so peak is about 311V.

Power in AC: P = V_rms × I_rms = V²_rms/R. Meters measure RMS values. Peak values are important for component ratings (insulation must withstand peaks).

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