A rocket in deep space ejects gases with speed 100 m/s relative to itself. Its mass decreases from M0 to M0/2. If its increase in speed is N ln2 m/s, find N.

Question

G1 Physics · Accepted Answer

Use the ideal rocket equation: Δv = u ln(M_initial/M_final). Here, u = 100 m/s, M_initial = M0, M_final = M0/2. Therefore Δv = 100 ln[M0/(M0/2)] = 100 ln2 m/s. Comparing with N ln2 m/s gives N = 100.