Final answer:
Only the shoes on a shoe rack have balanced forces acting on them, as they are not moving and the forces of gravity and the normal force from the shoe rack are equal and opposite. The other scenarios involve unbalanced forces since they include acceleration or a change in direction.
Step-by-step explanation:
The question Which of the following have balanced forces acting on them? pertains to Newton's First Law of Motion and the concept of equilibrium in physics. To identify the scenarios with balanced forces, we must consider whether the objects are in a state of rest or moving with a constant velocity, in which case the net external force is zero, as stated by Newton's First Law of Motion.
- A skateboarder speeding up as they ride down a hill is not an example of balanced forces because the skateboarder is accelerating due to the force of gravity, which is greater than the force of friction opposing the motion.
- Shoes resting on a shoe rack are an example of balanced forces since they are at rest, with the gravitational force being balanced by the normal force of the rack.
- A car turning a corner is not experiencing balanced forces as there is a centripetal force causing it to change direction, even if it's moving at a constant speed.
- A car traveling at a constant speed could be an example of balanced forces if it is in dynamic equilibrium, meaning that the engine's propulsion force is balanced by the air resistance and friction forces, resulting in no net force and thus no acceleration.