A car cruises down the highway. Its tires are rolling, not skidding.
Rowan calls the friction on them kinetic, because the car is clearly moving. The name is wrong, and one question shows why.
Static or kinetic is decided at the surfaces, never by the object.
Ask one question, and ask it where the surfaces touch, not where the object goes: are the two touching surfaces sliding across each other?
Follow one patch of the rolling tire. It touches the road, carries the car for a moment, and lifts away without ever sliding over the road.
No sliding between the surfaces, so the friction is static, even though the car is moving.
The tires of a car rolling without skidding experience static friction.
A skidding tire is different. Its rubber slides across the road, so the friction is kinetic.
The object's motion can fool you; the surfaces never do.
A crate rides on the bed of a moving truck. If the crate is not sliding on the bed, the friction between the crate and the bed is static.
So the sort is one question long: sliding between the surfaces gives kinetic friction; no sliding gives static friction, moving or not.
A dancer's shoe slides across the stage during a spin. Which friction acts between shoe and stage?
Ask the one question: are the two surfaces sliding across each other?
The shoe slides across the stage: yes.
Sliding gives kinetic friction.
Kinetic friction.
Tilda pedals her bike at a steady speed, and its wheels roll without skidding. Which friction acts between the tires and the road?
Ask the one question at the surfaces: is the tire's contact patch sliding across the road?
Rolling without skidding means no: each patch of tire touches down and lifts away without sliding.
No sliding gives static friction, even though the bike is moving.
Static friction.
A phone slides across a car's dashboard as the car turns. Which friction acts between the phone and the dashboard?
A planter sits on a sloped patio, staying put. Which friction acts between the planter and the patio?
A skateboard's wheels roll along the sidewalk without skidding. Which friction acts between the wheels and the sidewalk?
An ice skater glides across the rink on one blade. Which friction acts between the blade and the ice?
A toolbox rides on the bed of a pickup moving at a steady 50 mi/h, without sliding on the bed. Which friction acts between the toolbox and the bed?
A car brakes hard and its tires skid along the pavement. Which friction acts between the tires and the pavement?
In which case is the friction between the named surfaces static?
A bike rolls along without skidding. Then the rider locks the rear wheel, and its tire skids along the road. Which statement names the friction on the rear tire during the skid?
Which question decides whether the friction between two touching surfaces is static or kinetic?