Acceleration = (change in speed) / (time for the change)
Change in speed = (speed at the end) - (speed at the beginning)
= (140 km/hr) - (10 km/hr) = 130 km/hr
Time for the change = 50 sec
Acceleration = (130 km/hr) / (50 sec) = 2.6 km/hr per second.
To convert to more familiar units:
(2.6 km/hr-sec) x (1000 m/km) x (1 hr/3600 sec)
= (2.6 x 1000 x 1) / (3600) km-m-hr / hr-sec-km-sec
= 0.722 m/s² (about 0.074 of a G)
