Arocket's acceleration is 6.0 m/s2. assuming it starts at 0 m/s, how long will it take for the rocket to reach a velocity of 42 m/s?

Alright! Here's how we do it, the rockets acceleration is 6 m/s^2. This means that for every second that goes by, the rocket increases it's speed by 6 m/s. So, you simply divide 42 by 6:

42/6 = 7.

So assuming the rocket starts at 0. The rocket will take 7 seconds to reach the velocity of 42 m/s.