Answers

2015-12-05T18:49:08+08:00
Speed is equal to distance over time in the equation a=d/t where a is acceleration, d is the distance and t is the time.

a=614/12
a=51.1666667
whereas a has unit that depends on the given distance over time.
a=51.1666667 km/h
0
The given only requires rate of speed, a scalar quantity given the distance over time.  Acceleration is a vector quantity and involves change in velocity over time.  What is required is speed, not acceleration.  While your final answer is right, 51.17 km/hr, it is not acceleration. :-)