Answer:
125000 m/s
Step-by-step explanation:
From the law of conservation of linear momentum, the sum of initial and final momentum are zero. Momentum is given as p=mv where p represent momentum, m is mass of an object and v is the velocity. In this case, the initial momentum is zero since both are stationery. The final momentum sums should also be zero.
Final momentum
Mass of superman*speed + Mass of spaceship*speed of spaceship=0
150v+(125000*150)=0
150v=(12500*-150)
v=-12500 m/s
Therefore, the superman will have a speed of 12500 m/s in opposite direction of the spaceship