A \(5000 \mathrm{~kg}\) rocket is set for vertical firing. The exhaust speed is \(800 \mathrm{~m} \mathrm{~s}^{-1}\). To give an initial upward acceleration of \(20 \mathrm{~m} \mathrm{~s}^{-2}\), the amount of gas ejected per second to supply the needed thrust will be \(\left(g=10 \mathrm{~m} \mathrm{~s}^{-2}\right)\)
(a) \(185.5 \mathrm{~kg} \mathrm{~s}^{-1}\)
(b) \(187.5 \mathrm{~kg} \mathrm{~s}^{-1}\)
(c) \(127.5 \mathrm{~kg} \mathrm{~s}^{-1}\)
(d) \(137.5 \mathrm{~kg} \mathrm{~s}^{-1}\)