Answer:
First there is a need to convert 80.0 km/h to m/s. It is equivalent to (200 / 9) m/s. Because the body stops after 4.25 seconds, its acceleration is -(200/9/4.25) m/s^2. The needed force to stop the 2500 kg truck is equal to the product of its mass and its acceleration.
Solving for the net force to stop the 2500 kg truck
Force = mass * acceleration
Force = 2500 kg * -(200/9/4.25) m/s^2
Force = −13072 N or about −13.07 kN
The force exerted on the truck is −13072 N or about −13.07 kN