Final answer:
The velocity of the spaceship 5 seconds after the rockets fire is 265.0î m/s.
Step-by-step explanation:
To find the velocity of the spaceship 5 seconds after the rockets fire, we need to integrate the acceleration function over time. Given that the initial velocity is 250.0î m/s and the acceleration is (3.0î + 4.0k) m/s², we can integrate the x-component of the acceleration to find the change in velocity in the x-direction. By integrating 3.0î with respect to time, we get 3.0tî. Plugging in t = 5, we get 3.0(5)î = 15î m/s. Adding this to the initial velocity gives us 250.0î m/s + 15î m/s = 265.0î m/s.