Final answer:
The amount of friction between a couch and the floor is affected by the presence of additional weight (e.g., a person on the couch), varying floor surfaces, and the inherent weight of the couch itself. Answer D, 'All of the above affect friction,' is correct.
Step-by-step explanation:
When attempting to move a couch across the room with a friend sitting on it, several factors can change the amount of friction between the couch and the floor. The correct answer to what affects friction is D. All of the above affect friction:
- The presence of your best friend on the couch increases the overall weight of the couch, thereby increasing the normal force and consequently the friction between the couch and the floor.
- The type of floor surface also affects friction because different materials have different levels of roughness and adhesion, which contribute to varying frictional forces.
- The weight of the couch itself affects friction because the heavier the couch, the greater the normal force and the higher the friction force needed to start and keep the couch moving.
Overall, the frictional force is influenced by several factors such as mass, surface roughness, and material characteristics that affect adhesion and surface interaction.