Unbalanced Forces
2 guided lessons · 18 checks · 1. Forces & Motion → Forces, Movement & Changing Shape
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Balanced and unbalanced forces
Forces on one object combine along each line into a single resultant. When that resultant is zero the forces are balanced and nothing about the motion changes; when a surplus survives, the forces are unbalanced and the object must accelerate. This lesson fixes both words with the two standard scenes.
What you know already
A book on a desk and a tug-of-war rope tell one story in two halves: sometimes the forces cancel, sometimes they leave a surplus. This note names the two cases, then turns the surplus into the most used equation in mechanics — force equals mass times acceleration.
Key points of understanding
- Balanced forces cancel completely, so the resultant force on the body is zero.
- A book on a desk shows the standard balance: its weight downward against the desk's upward push.
- Unbalanced forces leave a resultant, and that resultant causes the object to accelerate.
- The acceleration may show as speeding up, slowing down, or changing direction.
- A tug-of-war with 80 N against 100 N leaves a 20 N resultant towards the stronger side.
A book resting on a table is an example of balanced forces
A tug-of-war is an example of when forces can become unbalanced
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1.Balanced and unbalanced forces
Forces on one object combine along each line into a single resultant. When that resultant is zero the forces are balanced and nothing about the motion changes; when a surplus survives, the forces are unbalanced and the object must accelerate. This lesson fixes both words with the two standard scenes.
A book resting on a table is an example of balanced forces
A tug-of-war is an example of when forces can become unbalanced
Key points
- Balanced forces cancel completely, so the resultant force on the body is zero.
Guided content from the SME authoring corpus — note rn_gDy2qTkY26r5sMtd, pinned at bfae99778094 · promoted SyllabAI/syllabai-resources b3caaaa90c5e