Final answer:
It is hardest to push the toy car across the carpet due to increased friction, which is the resistance encountered when moving one surface over another. Higher frictional force on carpeted surfaces requires more effort, thereby increasing the amount of work done when pushing the car compared to smoother surfaces like wood or tile.
Step-by-step explanation:
The reason it is hardest to push the toy car across the carpeted floor is most likely due to friction. Friction is the resistance that one surface or object encounters when moving over another. The carpet has a rougher texture than the wooden or tile floors, which increases the amount of friction between the car's wheels and the surface. This higher frictional force requires more effort to push the car across the carpet than smoother surfaces where the friction is less.
In physics, when you exert a force over a distance, you are doing work. The more force that is required to move an object across a surface, the more work you will do for the same distance. Since carpet has a higher frictional force, more work is done when pushing the same toy car across it compared to smoother surfaces.
The heat you feel when pushing objects like cardboard boxes across carpets is due to molecular interactions. As molecules in the cardboard box rub against those in the carpet, friction converts some of the kinetic energy into thermal energy, causing the surfaces to warm up.