A rocket has total mass 1000 kg with fuel of 900 kg. It ejects fuel at the rate of 1 kg/s with an exhaust velocity of `2 km//s` relative to rocket. The maximum velocity attained by rockct is:

Options

A. `2.3 km//s`
B. `4.6 km//s`
C. `2 km//s`
D. `4.6 log_(10) (10)/(9) km//s`

Answer

b

Explanation

Burnt-out speed, `upsilon_(b) = 2.303 u log(m_(0))/(m_(c))`
`=2.303xx2km//sxxlog(1000)/(1000-900)`
`=4.6km//s.  (log_(10)10=1)`
Hence correct choice is (b).