Which friction describes objects that do not move due to weight on a surface?

• A. Sliding friction
• B. Rolling friction
• C. Air Resistance
• D. Static Friction

Answer: (D)

Static friction is the force that prevents an object from moving when it rests on a surface. When the object’s weight presses it down, the surface pushes back with a normal force, and static friction acts opposite to the direction the object would slide. It can adjust its strength up to a maximum value, enough to balance the weight and any small push. If the forces trying to move the object stay below that maximum, the object stays at rest. If the push becomes large enough to exceed static friction, motion starts and the friction that acts while sliding—kinetic friction—takes over. Rolling friction would apply to objects that roll, not a block that isn’t moving; air resistance only matters when moving through air; sliding friction refers to motion between surfaces, not at rest. So the description of objects not moving because of weight on a surface points to static friction.