Which of the followings are the correct S.I. units of the quantities indicated? I. Thrust (N) II. Impulse \(\left( Kg m s ^{-1}\right)\) III. Energy density (J) IV. Electromotive force \(ML ^{2} T ^{-3}\).
A. I and III only B. II and III only C. I, II and IV only D. I, III and IV
Correct Answer: C
Explanation
- Thrust is force and it is measured in Newton (N) - Impulse \(=\) force \(\times\) time \(= kgm / s ^{2} \times s = kgms ^{-1}\) - Energy density $$ \begin{aligned} &=\frac{\text { energy }}{\text { volume }}=\frac{\text { force } \times \text { distelur }}{\text { volur }} \\ &=\frac{ Kgm ^{2} s ^{-2}}{ m ^{3}}=\frac{ Kgs ^{-2}}{ m } \\ &= Kgm ^{-1} s ^{-2} \text { or } Jm ^{-3} \end{aligned} $$ - Electromotive force $$ \begin{aligned} &=\frac{\text { work }}{\text { charge }}=\frac{\text { work }}{\text { current } \times \text { time }} \\ &=\frac{M L^{2} T^{-2}}{I \times T}=M L^{2} T^{-3} I^{-1} \end{aligned} $$
