Hollis tows a wagon down the sidewalk, his little cousin riding in it. Here is the wagon's free-body diagram, already drawn.
A finished free-body diagram holds a lot of information. What can you read off it?
Read a free-body diagram in three passes: name the forces, compare the arrow lengths, then say which direction wins.
First, the names. The labels carry them: the force from Hollis, rightward; friction, leftward; the weight, down; the normal force, up.
Second, the lengths. A longer arrow means a bigger force.
On this diagram the up arrow and the down arrow are equal: the normal force matches the weight.
The rightward arrow is longer than the leftward one: the force from Hollis beats friction.
The diagram shows a box being lifted by a rope. Which direction wins?
Third, the verdict, one line at a time.
Up against down: equal arrows, so neither direction wins.
The diagram shows a wind chime hanging from a hook. Which direction wins?
Right against left: the longer arrow wins, so rightward wins overall.
Any free-body diagram reads the same way: names from the labels, sizes from the lengths, and the winner from the longer arrow on each line.
The diagram shows a mop being pushed across a floor, with equal vertical arrows. Which direction wins overall?
A hanging planter's diagram shows a tension arrow up, drawn longer than its weight arrow down. Read the diagram: which direction wins?
Name the forces: a tension up, the weight down.
Compare the lengths: the up arrow is longer.
The longer arrow wins its line.
The tension beats the weight; upward wins.
A canoe is dragged over sand. Its diagram shows the force from Demi leftward, a shorter friction arrow rightward, and equal weight and normal-force arrows. Which direction wins overall?
Name the forces: the force from Demi, friction, the weight, the normal force.
Up against down: equal arrows, so neither wins.
Left against right: the leftward arrow is longer.
Leftward wins overall.
The diagram shows a loaded garden cart being pulled. Which statement reads the diagram correctly?
The diagram shows a hanging basket at rest. Which pair of forces does it show?
On a diagram of a falling pinecone, the drag arrow is drawn shorter than the weight arrow. What does the length difference say?