Final answer:
The horizontal component of the rocket's velocity is 106.07 m/s.
Step-by-step explanation:
To break down the velocity vector of the rocket launched northeast, we need to find its horizontal (x) component. The velocity can be broken down into its x and y components using trigonometry. Since the angle of launch is 45 degrees above the horizontal, the x and y components will be equal. The horizontal component of the rocket's velocity can be calculated using the equation Vx = V * cos(theta), where Vx is the horizontal component, V is the velocity, and theta is the angle of launch. Substituting the given values into the equation, we have Vx = 150 m/s * cos(45°) = 106.07 m/s.