Accelerating at the rate of 50 m/s² for 3 sec, it adds 150 m/s of speed. It was going 10 m/s before it started accelerating, so after adding another 150 m/s, it's going<u><em> 160 m/s. </em></u>
(That's speed, not velocity. There's not enough information in the question to allow us to describe its velocity ... we don't know what direction it's headed at any time during the story, and we don't know whether it accelerates all in a straight line.)
Now ... even though we did the math, and we answered the question, and it didn't ask us to do anything else ... let's look this story over and see whether it could actually happen in the real world.
... <u><em>It starts out going 10 m/s. </em></u> Nothing wrong with that. It's only about 22 miles per hour. A little too fast for a school zone, but it could sail right through a residential neighborhood at that speed and nobody would mind.
... <u><em>Mr. Cool in his Ferrari mashes the pedal to the medal and accelerates at a rate of 50 m/s² for 3 seconds.</em></u> That's 5.1 G's ! Even if his engine and tires could deliver that kind of performance, I'm not sure Enzio could stand it. And even if he could, he'd better keep going, because Bert and Ernie in their squad car are watching his smoke as he flames down the main drag, and as soon as he stops, they'll be all over him like the paint on his fenders.
... <u><em>His final speed is 160 m/s</em></u>. I don't think so. That's 358 miles per hour !
