Arocket lift off the surface of earth with a constant acceleration of 20 m/sec^2 .how fast will the rocket be going 1 min latter?

"Acceleration of 20 m/s² " means that the rocket is speeding up,
and its speed becomes 20 m/s greater every second.

Since it started out with zero speed, its speed after 1 minute
(60 seconds) is

              (20 m/s /s) · (60 s)  =  1,200 m/s .