Mostly chemical energy from the fuel.
A stationary truck has potential energy, which is energy that is stored in an object due to its position or configuration.
The kinetic energy of a truck can be increased without increasing its speed by increasing its mass. This can be done by loading the truck with heavier cargo. Kinetic energy is directly proportional to an object's mass, so increasing the truck's mass will result in an increase in its kinetic energy.
A moving truck is not a form of potential energy. Potential energy refers to the energy that is stored in an object due to its position or condition, such as gravitational potential energy or elastic potential energy.
The truck had kinetic energy as it rolled down the ramp because it was in motion. Kinetic energy is associated with the movement of an object.
potential
potential
The truck - greater mass.
The truck's kinetic energy is increasing as it gains speed downhill due to its motion. The gravitational potential energy of the truck is being converted into kinetic energy as it moves downhill, with the conversion being more pronounced the steeper the incline.
When they're parked they do (which is zero). If a truck and golf cart were both moving at the same non-zero speed, the truck, being more massive, would have the greater kinetic energy.
potential energy changes to kinetic energy
A truck moving at 60 mph has more kinetic mechanical energy than a bicycle moving at 15 mph due to the truck's higher mass and velocity. Kinetic energy is proportional to an object's mass and to the square of its velocity.
Kinetic energy keeps a toy truck rolling after it is pushed. Because kinetic energy is known as the energy of motion or action. -Angelikah Medina -8-Hyacinth (ERHS)