Answer
$1200 m/sec$.
Work Step by Step
Step 1. Given $\frac{dv}{dt}=a=20m/s^2$, we have $v(t)=20t+C$ where $C$ is a constant.
Step 2. Since at $t=0, v=0$, we have $20(0)+C=0$ and $C=0$, thus $v(t)=20t$
Step 3. At $t=1min=60sec$, we have $v(60)=20(60)=1200 m/sec$.
