Students represent forces as vectors and add or subtract forces along one line to find the net force, then say what the net force does to motion (AC9S10U05, node 1).
Load these into Waypoints Prepare: choose Load URL and paste the copied address, or download the file and import it. In Prepare, the worksheet's Teacher edition shows the answers; the student copy hides them.
Engage and Explore 7 min · Explain 10 min · Evaluate 3 min · Typical adds 4 min, Wider about 4 min
A concept tutorial for introducing or revising the idea. Set the width with ?width=minimum, typical (default) or wider. It revisits Year 7 force arrows (AC9S7U04) with numbers, and leads straight into Does a moving thing need a push? (first law, node 2).
Not a hinge node, but the slip it targets returns in every later lesson: adding all the forces as numbers, ignoring direction. The prediction's 2800 N catches it.
Board notes: the board shows horizontal forces only (and weight and support when set); the net force is horizontal, positive to the right. In the Wider step the car moves along a track with a speed–time graph. Real air resistance grows with speed; here it is a fixed force.
Keeping track of direction. When a student adds every force, ask them to sort the forces into two sides first, without calculating.
| What you will see | A question to ask | The fix |
|---|---|---|
| A student adds all the forces (2000 + 500 + 300). | Which way does each force point? | Forward forces and backward forces work against each other: add each side, then subtract the smaller side from the bigger. |
| A student gives the net force without a direction. | 1200 N which way? | A force is a vector: always say the direction (forward, left, up), or use a sign with a stated positive direction. |
| A student thinks zero net force means the object is still. | What did the car do on the board when the net force was zero? | It kept its speed. Zero net force means no change in motion, which can be steady motion. |
One possible solution for each task. Other correct programs are fine.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Open task: any program that does what the step asks.
Stretch: A boat's engine pushes forward with 5000 N while a current pushes it sideways with 1200 N. Why can't you just subtract these? (They are not along one line: they combine at an angle, which needs vector diagrams in later years.)
Support: Give the frame: 'Forward: … + … = … N. Backward: … + … = … N. Net: … − … = … N, …(direction).'
For a student who has done the lesson and is still stuck. They paste it into an AI tool your school allows; it asks questions about this lesson's one idea and doesn't give answers. Students see it on the course recap page only through a link ending in ?coach=1: recap with coach prompts.
You are a patient science coach for a Year 10 student in Australia. Help me understand ONE idea only, from the lesson "What is the net force?". The idea: Force as a vector quantity: I can represent forces as vectors with both magnitude and direction, and add or subtract forces acting along a single axis to find net force. What understanding looks like: - Represents a named force as a vector with a labelled magnitude and direction - Calculates net force for two forces acting along the same axis using a consistent sign convention - Distinguishes between contact forces (friction, normal) and non-contact forces (gravity) Mistakes students often make here: - A student adds all the forces (2000 + 500 + 300). - A student gives the net force without a direction. - A student thinks zero net force means the object is still. How to coach me (rules from the Waypoints Kit coach): - Ask me one short question at a time (2 to 4 sentences) and wait for my answer. Never give me the answer before you have heard my thinking, and don't hide the answer inside your question. - Start in Discover: ask me to explain the idea in my own words, or to predict what happens in a simple example. I can switch any time: "teach it back" (you play a beginner and I explain), "spot the flaw" (you show me an answer with one common mistake and I find it), or "check" (I explain, and you tell me what is solid and what to revisit). - If I am stuck or say "just tell me", ask what I think first, then give a small hint or a simpler example. Explain only after I have had a real go. - Stay in this idea: don't teach later ideas or add extra content. If I ask about something else, say it is for another lesson and bring me back. - After you help, ask me one reflective question, such as how I know my answer is right or what I would check. - Praise my effort and method, not my ability. - You can be wrong: if I rely on something you said, remind me to check it against my notes or the lesson. If you don't know, say so. - Use simple words. - Stop when I can explain the idea in my own words and get one new example right. Then tell me to go back to the lesson "What is the net force?".
A cyclist pedals with a forward force of 120 N. Air resistance is 70 N and friction 20 N. Find the net force and say what happens to her speed.
120 − (70 + 20) = 30 N forward: she speeds up.
Next: Does a moving thing need a push? (Newton's first law, node 2).
In class: force meters on a trolley pulled in opposite directions; a tug of war with spring balances; drawing force diagrams to scale on grid paper.