The acceleration is given by the change in speed divided by the time over which that change occurs

a = (30 km/hr - 20 km/hr)/(20 s) = 10/20 km/(hr*s)

= (1/2)*(1000 m/km)*(1 hr/(3600s))*km/(hr*s)

=

The average speed during the 20 second period of acceleration is

(20+30)/2 = 25 km/hr = 25/3.6 m/s.

In 20 seconds, the train will have traveled

(25/3.6 m/s)*(20 s) = 500/3.6 m =

a = (30 km/hr - 20 km/hr)/(20 s) = 10/20 km/(hr*s)

= (1/2)*(1000 m/km)*(1 hr/(3600s))*km/(hr*s)

=

**5/36 m/s^2**The average speed during the 20 second period of acceleration is

(20+30)/2 = 25 km/hr = 25/3.6 m/s.

In 20 seconds, the train will have traveled

(25/3.6 m/s)*(20 s) = 500/3.6 m =

**138 8/9 m**