
The rate of change of velocity per unit time is called acceleration.
Its SI unit is m/s².

We will have the following:

So, the heat to add is 3611.52 Joules.
Explanation:
Average speed = distance / time
|v| = (7 km + 2 km) / (2 hr + 1 hr)
|v| = 3 km/hr
Average velocity = displacement / time
v = (7 km east + 2 km east) / (2 hr + 1 hr)
v = 3 km/hr east