[Coda]

Δx = 1/2(vi + vf)Δt

The change in position equals the average velocity multiplied by the change in time. In this case, you're using constant acceleration, so the average velocity can be found by averaging the initial and final velocities.

Impulse is a measurement of the change in momentum caused by a force applied over time. A big force over a short time can have the same impulse -- that is, the same change in momentum -- as a small force over a long time. In the case of a constant force, it's just F*Δt.