Acceleration = (change in speed) / (time for the change)
Change in speed = (speed at the end) - (speed at the beginning)
Change in speed = (Zero) - (24 km/hour)
Change in speed = (-24 km/hr)
Acceleration = (-24 km/hr) / (3 sec)
Acceleration = -8 km/hr-sec
To give it more familiar units, multiply it by (1 hr / 3600 sec)
Acceleration = (-8 km/hr-sec) x (1hr / 3600sec)
Acceleration = (-8/3600) km/sec²
Acceleration = -0.0022... km/sec²
Acceleration = -2.2... m/s²
