The final velocity of the truck is found as 146.969 m/s.
Explanation:
As it is stated that the lorry was in standstill position before travelling a distance or covering a distance of 3600 m, the initial velocity is considered as zero. Then, it is stated that the lorry travels with constant acceleration. So we can use the equations of motion to determine the final velocity of the lorry when it reaches 3600 m distance.
Thus, a initial velocity (u) = 0, acceleration a = 3 m/s² and the displacement s is 3600 m. The third equation of motion should be used to determine the final velocity as below.

Then, the final velocity will be

Thus, the final velocity of the truck is found as 146.969 m/s.
The molecules of a solid vibrate faster so that they start spreading out to become a liquid. This energy makes them vibrate faster so the bonds between molecules can't interact all that well anymore creating more distance. The stronger the bonds between the molecules the higher the energy (temperature) has to be to get them away from each other. Hope I didn't confuse you too much!
It'd be an unbalanced force
Initial velocity = Vo= 25 m/s
Final velocity = V = x
Acceleration= a = 6 m/s^2
time= t = 4 seconds
Appy the equation:
V = Vo + at
Replacing:
V = 25 + 6(4) = 25 + 24 = 49 m/s