Question

If the two stage rocket of a weights 100 kg and 10 kg separately and contains 800 kg and 90 kg fuel

separately, what is the final velocity that can be achieved with an exhaust velocity of 1.5 km/sec. (Given

log10 =2.3 and log102 =0.3 )

Answer 1

$m_1=100,~M_1=800,~m_2=10,~M_2=90,$

$v=v_0\ln\frac{m_1+M_2+m_2+M_2}{m_1+m_2+M_2}\ln\frac{m_2+M_2}{m_2}=5. 56~\frac{km}s.$