Final answer:
To stop the accelerating truck, a force equal to its mass multiplied by the acceleration needs to be applied. The force required to stop the truck is 10,500 N.
Step-by-step explanation:
To stop the truck from accelerating, we need to apply a force equal to its mass multiplied by its acceleration. The mass of the truck is 1400 kg and its acceleration is 7.5 m/s². Therefore, the force required to stop the truck is:
Force = mass × acceleration
Force = 1400 kg × 7.5 m/s²
Force = 10500 N
So, the correct answer is 10,500 N (C).