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Frictional force is a force that opposes the motion of objects sliding against each other. It acts in the opposite direction to the movement of the object. In the case of the loaded truck, as it travels on a level road, it has to continuously overcome this opposing force to maintain a constant speed.
This frictional force is exerted by the road on the truck, and it is given as 1000 N. Even though this may seem like a large force, the truck's engine is powerful enough to counteract it, allowing the truck to travel smoothly.
Understanding that the engine has to constantly do work not just to start the truck moving but also to keep it moving at a constant speed helps to grasp the notion of how frictional forces consume energy. This energy consumption is visible by the work done to maintain motion, which in this scenario, is calculated as the product of the frictional force and the distance traveled.

The gravitational force acts on objects with mass, pulling them towards the center of the Earth. In our scenario, gravity plays a significant role when the truck travels uphill after moving on a level road. Gravity's influence increases as the incline becomes steeper, requiring more work to climb than on flat terrain.
When a vehicle like the truck moves up an incline, its engine must do additional work against this gravitational pull. The gravitational force the truck faces is computed as the product of its mass and the acceleration due to gravity, which is approximately 9.8 m/s².
The work done against gravity further involves calculating the vertical distance ascended. The truck’s movement up the inclined plane is resisted by gravity, hence the need for more energy use to maintain the same speed uphill. As the vertical height entered was 1800 m on an incline, an understanding of how gravitational work is calculated deepens the awareness of energy expenditure during such uphill travels.

The concept of constant speed means that the velocity of an object remains unchanged over time - there are no accelerations or decelerations. For the truck, constant speed implies that the forces propelling and retarding its motion (like friction and gravity, respectively) are balanced.
Achieving and maintaining constant speed are crucial in this scenario, as it simplifies calculations related to work done. Since speed is steady, the truck's kinetic energy doesn't increase or decrease, meaning that all the work done by the engine is used to counteract external forces, primarily friction on a flat road and gravitational force uphill.
Understanding constant speed also highlights how balanced forces come into play. The truck maintains its speed even on an incline because the work done exactly matches the work required to overcome both friction and gravity, demonstrating the requirement for equilibrium in these scenarios.

An inclined plane is a flat surface tilted at an angle to the horizontal. It eases the effort needed to lift an object by spreading the work over a longer distance, though in this scenario, the inclined plane represents a hill the truck must climb.
When traversing an inclined plane, an additional component of gravitational force acts parallel to the surface, resisting the upward movement. This requires the truck's engine to do extra work to counteract gravity, apart from overcoming friction. The incline's angle ( 30° in this case) determines the steepness and thus the difficulty of the climb. The steeper the incline, the more work needs to be done to ascend at constant speed.
In practice, understanding how inclined planes function is critical for calculating work done in real-world scenarios, like the one provided. It helps us recognize how slopes transform forces and necessitate additional energy, which the engine must supply for sustained movement.