Drawing Force Diagrams
Draw and interpret force diagrams showing forces as labelled arrows — where the arrow's length represents the force's magnitude and its direction shows which way the force acts; show multiple forces on one object; identify from the diagram whether forces are balanced (equal arrows in opposite directions, no resultant) or unbalanced (arrows of different sizes, producing a resultant); represent the resultant with a single arrow
What a learner can do afterwards
- Draw a force diagram with labelled arrows showing direction and relative size for at least two forces acting on an object
- Use their diagram to explain whether forces are balanced or unbalanced and what will happen to the object
- Add a resultant force arrow to a diagram and explain how they calculated it
The lesson
A force diagram is a picture that shows every push and pull acting on an object. Each force is drawn as an arrow. The arrow's length shows how strong the force is, and the direction it points shows which way the force acts.
A book sits still on a table. Gravity pulls it down. The table pushes back up just as hard. Draw a short arrow down for gravity and a matching arrow up for the table's push. Same size, opposite ways: balanced. That is why the book stays put.
Now picture two kids pushing a box. One pushes right harder than the other pushes left. The arrows are different lengths, so the forces are unbalanced. The box moves the way the longer arrow points. Draw one new arrow, called the resultant, to show the size and direction of that leftover push.
When you draw a force diagram, label every arrow so you remember what it stands for. Compare the lengths first. If they match and point opposite ways, the object stays as it is. If one is longer, that is the way the object moves.
Every force gets an arrow, its length for strength and its direction for which way, and if they don't cancel out, one resultant arrow shows the leftover push.
Watch it
Where it sits
Learn first
Nothing; this is a starting point.
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.