Yusuf drags a sled rightward over packed snow.
The sled is moving now. What does its free-body diagram carry?
Start from the resting diagram you know: weight down, normal force up.
Yusuf's pull acts on the sled: one new arrow, rightward.
The sled slides rightward over the snow, so friction acts on it: one arrow, leftward, against the sliding.
The diagram now carries four arrows: weight down, normal force up, the pull rightward, friction leftward.
Demi drags a storage bin rightward across a garage floor. Which way does the friction arrow on the bin point?
Demi keeps dragging the bin rightward across the floor. Which forces appear on the bin's free-body diagram?
The vertical pair stays balanced. The sled neither sinks into the snow nor lifts off it, so those two arrows stay equal.
While the bin slides rightward, which vertical arrows stay on its diagram?
A pushed object builds the same way. Clara pushes a couch leftward over a wooden floor: weight, normal force, the force from Clara leftward, friction rightward.
Friction's arrow has one rule: point it against the sliding, whichever way the sliding goes.
Yusuf drags his sled rightward over the snow. Build the sled's free-body diagram.
The sled becomes a box.
Its weight: straight down. The snow's normal force: straight up, equal.
The pull from Yusuf: rightward.
The sled slides rightward, so friction points leftward.
Four arrows: weight down, normal force up, the pull rightward, friction leftward.
Clara pushes a couch leftward over a wooden floor. Build the couch's free-body diagram.
The couch becomes a box.
Its weight: straight down. The floor's normal force: straight up, equal.
The force from Clara: leftward.
The couch slides leftward, so friction points rightward.
Four arrows: weight down, normal force up, the force from Clara leftward, friction rightward.
A trash can is dragged rightward across pavement. Which set of arrows is its correct free-body diagram?
A duffel bag is dragged leftward across a gym floor. Which way does the friction force on the bag point?
A trash can is dragged rightward across pavement. Which object exerts the leftward friction force on the can?