To find the accelerating force, we can use Newton's second law of motion, which states that the force acting on an object is equal to the mass of the object multiplied by its acceleration:
Force = mass × acceleration
In this case, the mass of the truck is given as one tonne, which is equivalent to 1000 kilograms. The initial velocity of the truck is 25 m/s, and it accelerates uniformly to a final velocity of 60 m/s in 10 seconds. We can calculate the acceleration using the formula:
acceleration = (change in velocity) / time
Change in velocity = final velocity - initial velocity = 60 m/s - 25 m/s = 35 m/s
acceleration = 35 m/s / 10 s = 3.5 m/s²
Now we can substitute the values into the equation to find the accelerating force:
Force = mass × acceleration = 1000 kg × 3.5 m/s² = 3500 Newtons
Therefore, the accelerating force acting on the truck is 3500 Newtons.