일반물리학 2 — Electromagnetic Waves: Problem 53

53 A small spaceship with a mass of only $1.5 \times 10^3 \text{ kg}$ (including an astronaut) is drifting in outer space with negligible gravitational forces acting on it. If the astronaut turns on a $25 \text{ kW}$ laser beam, what speed will the ship attain in $45.0 \text{ day}$ because of the momentum carried away by the beam?