The Net Accelerating Force:
The net accelerating force is the difference between the force exerted by the engine and the frictional force offered by the track. In this case, the force exerted by the engine is 40000 N and the frictional force offered by the track is 5000 N. Therefore, the net accelerating force can be calculated as follows:
Net Accelerating Force = Force Exerted by Engine - Frictional Force
Net Accelerating Force = 40000 N - 5000 N
Net Accelerating Force = 35000 N

The Acceleration of the Train:
The acceleration of the train can be calculated using Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In this case, the mass of the engine is 8000 kg and the mass of each wagon is 2000 kg. Therefore, the total mass of the train can be calculated as follows:
Total Mass of Train = Mass of Engine + (Number of Wagons × Mass of Each Wagon)
Total Mass of Train = 8000 kg + (5 × 2000 kg)
Total Mass of Train = 8000 kg + 10000 kg
Total Mass of Train = 18000 kg

Now, we can calculate the acceleration of the train using the formula:
Acceleration = Net Accelerating Force / Total Mass of Train
Acceleration = 35000 N / 18000 kg
Acceleration ≈ 1.944 m/s²

The Force of Wagon 1 on Wagon 2:
To determine the force of wagon 1 on wagon 2, we need to consider the action-reaction principle of Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. In this case, the force exerted by wagon 1 on wagon 2 is equal in magnitude but opposite in direction to the force exerted by wagon 2 on wagon 1.

Since the train is moving in a straight line with a constant acceleration, the force of wagon 1 on wagon 2 can be calculated using the formula:
Force of Wagon 1 on Wagon 2 = Mass of Wagon 2 × Acceleration
Force of Wagon 1 on Wagon 2 = 2000 kg × 1.944 m/s²
Force of Wagon 1 on Wagon 2 ≈ 3888 N

Therefore, the force of wagon 1 on wagon 2 is approximately 3888 N.