What it does
A force is a push or a pull, and it has a direction. When several forces act on the same thing along a line, they add up: forces in the same direction add, forces in opposite directions take away. What is left is the net force. If the forces cancel (net force zero) they are balanced, and something at rest stays at rest. If they do not cancel they are unbalanced, and the object starts to move towards the bigger force.
This page shows it as a tug-of-war. Add children (100 N each) and adults (250 N each) to either side. The picture draws each team’s total pull as an arrow and the net force as a thick arrow underneath. Press Pull! and the rope moves only if the forces do not balance, faster when the difference is bigger.
It follows the school topics Class 8 Science, exploring forces (balanced and unbalanced forces, net force) and Class 9 Physics, force and laws of motion. Afterwards, newton's laws sandbox pushes a trolley with F = ma and friction, and the friction ramp adds friction on a slope.
How to use it
- Add pullers with + Child or + Adult on each side, or Remove one.
- Read each team’s total and the net force, then press Pull!.
- Press Back to the start to try another match.
- The Level switch (Class 9) adds the total mass, the acceleration a = F/m, the time to reach the winning line 2 m away (from s = ½at²) and the speed.
Worked example
Two adults on the right pull 2 × 250 = 500 N; one adult on the left pulls 250 N. Net force = 500 − 250 = 250 N to the right: unbalanced, so the rope moves right. The moving mass is three adults (3 × 65 = 195 kg) plus the 5 kg rope, 200 kg in all, so a = 250 ÷ 200 = 1.25 m/s². To move 2 m from rest takes t = √(2s/a) = √(4 ÷ 1.25) = 1.79 s.
Five children (500 N) against two adults (500 N) is a draw: the forces balance and the rope stays still, even though everyone is pulling hard.
Check yourself
Five fresh questions: the net force of two teams, which way the rope moves, forces in the same direction, a = F/m, and balanced forces on a book. Nothing is saved.
Tips
- Draw arrows: same direction, add; opposite, subtract.
- Balanced forces can also act on something already moving: it then keeps moving at a steady speed.
- In real tug-of-war, the team whose feet grip the ground better can win, because the ground pushes back on their feet.
FAQ
Why do both teams feel the same pull in the rope? The rope pulls each team with the tension in it. What decides the winner is the net force on the whole system, including each team’s push on the ground.
Are 100 N and 250 N real? They are rounded values for the game; real pulls vary a lot.
Is this from NCERT? No. It is an independent study aid that follows the same school topics, with its own pictures and numbers.
Where the numbers come from
- Forces along a line add as signed numbers; net force zero means balanced; Newton's second law a = F/m and s = ½at² from rest: standard school physics.
- Pulls of 100 N for a child and 250 N for an adult, and masses of 35 kg and 65 kg, are rounded, made-up values for the game.
- Checked by hand: net forces, accelerations and times for several teams.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-09.