Learning objectives
- I can explain and apply: Collinear resultant force.
- I can explain and apply: Weight and equilibrium.
- I can explain and apply: Action and reaction.
Greek Gymnasium Grade 2 / Physics / Two-unit revision pilot
Forces
Forces: structured theory, worked examples, answered practice, and a mastery checklist for Greek Gymnasium Grade 2.
CHAPTER PLAN
Learn, practise, and check your progress
Follow the steps in order or jump directly to the part you need.
—/5
completed
Estimated active study time
156 minutes
1. Understand
Objectives, key ideas, and structured theory.
Open →2. Follow the method
Worked examples that explain every step.
Open →3. Practise
Graded tasks with hints and answer guidance.
Open →4. Consolidate
Assignments from core work to challenge.
Open →5. Check
A timed, marked test with solution guidance.
Open →
Progress is stored only in this browser and does not require AI credits.
Key ideas and checks
- The newton is a force unit, not a mass unit.
- W=mg, using g=10 N/kg where specified here.
- ΣF=0 does not necessarily mean v=0.
Unit
Core theory
The essential chapter ideas in a clear sequence before practice.
Understanding the concept
A force has a body of application, direction and magnitude. Before combining forces, draw only those acting on the same body. Along one axis, use signs and interpret the resultant's direction.
Method and conditions
Weight is the gravitational force W=mg, measured in N. Mass is measured in kg. Zero resultant means rest or constant-velocity straight-line motion, depending on the initial state.
Checking and coverage boundaries
Action and reaction belong to the same interaction and act on different bodies. They therefore do not cancel on one body's free-body diagram. Weight and a table's normal force may balance, but are not an action–reaction pair.
Original pilot material — human educator review pending
Written specifically for YourFavTeacher with AI assistance, without copying past-paper prompts. Technical and numerical checks do not replace review by a human educator. It is not an official paper or endorsed by an examination body.
Physics
Worked examples
Follow the method step by step and check why every step is valid.
Worked example 1
A box experiences 12 N rightwards and 5 N leftwards. Find the resultant.
- 1Take rightwards as positive.
- 2ΣF=12−5=7 N
- 3Keep SI units and check the sign.
7 N →
Worked example 2
A body moves in a straight line at constant velocity. Is its resultant force or its velocity zero?
- 1Velocity does not change, but is not necessarily zero.
- 2Apply Newton's first law in an inertial reference frame.
- 3Balanced forces are compatible with uniform motion.
Zero resultant force, not necessarily zero velocity.
Worked example 3
A body experiences 6 N and 5 N rightwards, and 11 N leftwards. Calculate the resultant.
- 1Add all forces algebraically along the same axis.
- 2ΣF=6+5−11=0 N
- 3We cannot infer rest without knowing the initial velocity.
0 N
Forces
Practice with answers
Eight graded tasks from core fluency to exam-style application. Work independently before opening a hint or answer.
Core fluency6 minutes
A box experiences 6 N rightwards and 2 N leftwards. Find the resultant.
Hint
Take rightwards as positive.
Answer guide
Take rightwards as positive. ΣF=6−2=4 N Keep SI units and check the sign. 4 N →
Core fluency6 minutes
A body of mass 3 kg is on Earth with g=10 N/kg. Find its weight.
Hint
Weight is a force, not mass: W=mg.
Answer guide
Weight is a force, not mass: W=mg. B=3·10=30 N The direction is vertically towards Earth's centre. 30 N
Core fluency6 minutes
A stationary box experiences 3 N rightwards. What horizontal force is needed for equilibrium?
Hint
Equilibrium requires zero resultant.
Answer guide
Equilibrium requires zero resultant. 3+F=0 ⇒ F=−3 N The negative sign denotes leftwards. 3 N ←
Application6 minutes
A book rests on a table. Are its weight and the normal force an action–reaction pair?
Hint
Both forces act on the same body, the book.
Answer guide
Both forces act on the same body, the book. An action–reaction pair acts on different bodies. A pair is the table's force on the book and the book's force on the table. No; the forces on the book can balance without forming such a pair.
Application6 minutes
A body moves in a straight line at constant velocity. Is its resultant force or its velocity zero?
Hint
Velocity does not change, but is not necessarily zero.
Answer guide
Velocity does not change, but is not necessarily zero. Apply Newton's first law in an inertial reference frame. Balanced forces are compatible with uniform motion. Zero resultant force, not necessarily zero velocity.
Application6 minutes
A force meter has 3 equal intervals from 0 to 6 N. What force do 2 intervals indicate?
Hint
First calculate the value of one interval.
Answer guide
First calculate the value of one interval. 6/3=2 N; 2·2=4 N Count intervals, not tick marks including zero. 4 N
Reasoning6 minutes
A student says friction always acts leftwards. Explain why this is not a general rule.
Hint
Left/right depends on the chosen axis.
Answer guide
Left/right depends on the chosen axis. Kinetic friction opposes relative sliding of the surfaces. If sliding reverses, friction reverses too. Use the direction of relative sliding, not a fixed leftwards rule.
Reasoning6 minutes
A body experiences 3 N and 2 N rightwards, and 5 N leftwards. Calculate the resultant.
Hint
Add all forces algebraically along the same axis.
Answer guide
Add all forces algebraically along the same axis. ΣF=3+2−5=0 N We cannot infer rest without knowing the initial velocity. 0 N
Common mistakes
- Adding forces acting on different bodies.
- Giving weight in kg.
- Assuming zero resultant always means rest.
Mastery check
- I can solve independently and check: Collinear resultant force.
- I can solve independently and check: Weight and equilibrium.
- I can solve independently and check: Action and reaction.
Forces
Chapter homework
Six distinct assignments from core fluency to challenge, each with an estimated time, hint, and answer guide.
Core8 minutes
A box experiences 8 N rightwards and 3 N leftwards. Find the resultant.
Hint
Take rightwards as positive.
Answer guide
Take rightwards as positive. ΣF=8−3=5 N Keep SI units and check the sign. 5 N →
Core8 minutes
A body of mass 4 kg is on Earth with g=10 N/kg. Find its weight.
Hint
Weight is a force, not mass: W=mg.
Answer guide
Weight is a force, not mass: W=mg. B=4·10=40 N The direction is vertically towards Earth's centre. 40 N
Stretch8 minutes
A stationary box experiences 4 N rightwards. What horizontal force is needed for equilibrium?
Hint
Equilibrium requires zero resultant.
Answer guide
Equilibrium requires zero resultant. 4+F=0 ⇒ F=−4 N The negative sign denotes leftwards. 4 N ←
Stretch8 minutes
A book rests on a table. Are its weight and the normal force an action–reaction pair?
Hint
Both forces act on the same body, the book.
Answer guide
Both forces act on the same body, the book. An action–reaction pair acts on different bodies. A pair is the table's force on the book and the book's force on the table. No; the forces on the book can balance without forming such a pair.
Challenge8 minutes
A body moves in a straight line at constant velocity. Is its resultant force or its velocity zero?
Hint
Velocity does not change, but is not necessarily zero.
Answer guide
Velocity does not change, but is not necessarily zero. Apply Newton's first law in an inertial reference frame. Balanced forces are compatible with uniform motion. Zero resultant force, not necessarily zero velocity.
Challenge8 minutes
A force meter has 4 equal intervals from 0 to 8 N. What force do 3 intervals indicate?
Hint
First calculate the value of one interval.
Answer guide
First calculate the value of one interval. 8/4=2 N; 3·2=6 N Count intervals, not tick marks including zero. 6 N
45 minutes / 40 marks
Full chapter test
A timed, full-mark self-assessment with model-answer guidance.
Show working, units and a final check. Equivalent correct methods are accepted. Timing is a revision guide, not official examination conditions.
1. A box experiences 10 N rightwards and 4 N leftwards. Find the resultant.
5 marksAnswer guide
Take rightwards as positive. ΣF=10−4=6 N Keep SI units and check the sign. 6 N →
2. A body of mass 5 kg is on Earth with g=10 N/kg. Find its weight.
5 marksAnswer guide
Weight is a force, not mass: W=mg. B=5·10=50 N The direction is vertically towards Earth's centre. 50 N
3. A stationary box experiences 5 N rightwards. What horizontal force is needed for equilibrium?
5 marksAnswer guide
Equilibrium requires zero resultant. 5+F=0 ⇒ F=−5 N The negative sign denotes leftwards. 5 N ←
4. A book rests on a table. Are its weight and the normal force an action–reaction pair?
5 marksAnswer guide
Both forces act on the same body, the book. An action–reaction pair acts on different bodies. A pair is the table's force on the book and the book's force on the table. No; the forces on the book can balance without forming such a pair.
5. A body moves in a straight line at constant velocity. Is its resultant force or its velocity zero?
5 marksAnswer guide
Velocity does not change, but is not necessarily zero. Apply Newton's first law in an inertial reference frame. Balanced forces are compatible with uniform motion. Zero resultant force, not necessarily zero velocity.
6. A force meter has 5 equal intervals from 0 to 10 N. What force do 4 intervals indicate?
5 marksAnswer guide
First calculate the value of one interval. 10/5=2 N; 4·2=8 N Count intervals, not tick marks including zero. 8 N
7. A student says friction always acts leftwards. Explain why this is not a general rule.
5 marksAnswer guide
Left/right depends on the chosen axis. Kinetic friction opposes relative sliding of the surfaces. If sliding reverses, friction reverses too. Use the direction of relative sliding, not a fixed leftwards rule.
8. A body experiences 5 N and 4 N rightwards, and 9 N leftwards. Calculate the resultant.
5 marksAnswer guide
Add all forces algebraically along the same axis. ΣF=5+4−9=0 N We cannot infer rest without knowing the initial velocity. 0 N
Unit
Official sources and verification
Curriculum reference sources. Always confirm the teaching sequence with the school and tutor.
Physics
Learn to read the question, choose the formula, write units, and explain the result.
What this chapter covers
The structure follows the official textbook layout and is used to organise study.
Collinear resultant force
Weight and equilibrium
Action and reaction
Where to focus
The areas that usually create mistakes or need extra revision.
I can solve independently and check: Collinear resultant force.
I can solve independently and check: Weight and equilibrium.
I can solve independently and check: Action and reaction.
Sources, daily material, and resources
Where to start: textbook, daily material, PDFs, videos, and worked examples.
Start from the official textbook or specification referenced on the subject page.
Use the notes and examples as support, not as a replacement for the official syllabus.
Check the current syllabus version before exam preparation.
Practice by subtopic
Targeted practice before full tests so coverage is clear.
A box experiences 6 N rightwards and 2 N leftwards. Find the resultant.
A body of mass 3 kg is on Earth with g=10 N/kg. Find its weight.
A stationary box experiences 3 N rightwards. What horizontal force is needed for equilibrium?
A book rests on a table. Are its weight and the normal force an action–reaction pair?
A body moves in a straight line at constant velocity. Is its resultant force or its velocity zero?
A force meter has 3 equal intervals from 0 to 6 N. What force do 2 intervals indicate?
A student says friction always acts leftwards. Explain why this is not a general rule.
A body experiences 3 N and 2 N rightwards, and 5 N leftwards. Calculate the resultant.
Mocks and progress checks
How to measure progress in this chapter and when it enters a cumulative mock.
Start with untimed practice by subtopic.
Move to a short timed checkpoint only after completing the mastery checklist.
Record each error with the correct method and revisit it after 48 hours.
Next step
What to do after finishing the chapter and how it connects to the next unit.
Complete the practice without support.
Explain the core method aloud in under two minutes.
Continue to the next chapter or request targeted tutor support.
Note: for the official examinable syllabus of each school year, always confirm with the school, tutor, and current Ministry/IEP announcements.