If a ferrari, with an initial velocity of 10 m/s,
accelerates at a rate of 50 m/s2
, for 3 seconds,
what was his ending velocity?

Acceleration at 50m/sec² :  means every second the velocity increases by 50 m/sec. In 3 seconds the velocity increases by 150 m/s. So total will be 160 m/sec.

the formula is

  V = final velocity  =  U initial velocity + acceleration a * time duration t

  V = 10 m/s + 50 m/sec² * 3 sec  =  160 m/sec