Final answer:
The energy for static friction to do work on a block on a truck moving in a circular path is supplied by the truck's engine. Static friction transfers this energy to the block, allowing it to move without sliding. The kinetic energy of the system changes with acceleration and deceleration, with energy leaving the system as heat due to friction when the truck stops.
Step-by-step explanation:
Understanding Work and Energy Transfer in a Circular Path
When a truck goes around in a circular path and stops after one revolution, the work done by static friction during the journey involves energy transfer. The energy needed for static friction to do work does not come from the friction itself, as it doesn't store energy. Rather, the energy comes from the engine of the truck which provides the force required to accelerate the block and the truck system around the circle. In this scenario, static friction is essential in transferring energy from the engine to the block, allowing it to maintain its motion without slipping off the truck.
In terms of energy transfer, when the truck is accelerating, the engine does positive work on the truck, increasing its kinetic energy. When the truck stops, that kinetic energy is gradually dissipated, primarily through negative work done by friction, which eventually causes the truck to come to a halt with the energy leaving the system typically in the form of heat. During circular motion at constant speed, the engine's force via static friction does not do work in the direction of motion, hence the kinetic energy remains constant.