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1.8.3States of Matter

Levers — Cambridge IGCSE Chemistry 0620 Revision Notes & Topical Questions

5 min read 5 parts Lesson 14 of 30 Unit quiz

📚 Cambridge IGCSE Chemistry 0620 Hub / Topical Revision
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Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
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Part 1 of 5How Levers Work

A lever is a rigid bar that turns about a pivot, and it makes a turning effect larger with a smaller effort.

Lever
  • Lever A rigid bar that rotates about a pivot, used to produce a larger turning effect than the force applied directly.
Force multiplier
  • Force multiplier A lever increases the output force by applying the input force at a greater distance from the pivot.
Effort
  • Effort The force applied to the lever by the user, which is often small compared with the force produced.
Load
  • Load The force the lever exerts on the object being moved, which is usually larger than the effort.

Part 2 of 5Examples of Levers

Examples of Levers
Bottle opener
  • Bottle opener A small upward effort at a distance from the pivot creates a larger upward force on the bottle cap.
Crowbar
  • Crowbar A small downward force applied far from the pivot creates a large upward force that lifts a heavy rock.
Wheelbarrow
  • Wheelbarrow The load sits between the wheel, which is the pivot, and the handles, so a small effort lifts a heavy load.
Spanner
  • Spanner A longer spanner increases the moment produced by the same effort, which makes a bolt easier to turn.

Part 3 of 5Improving a Lever

The moments on either side of the pivot determine how well a lever works.

1
Increase the size of the effort force, which increases the moment produced at the same distance.
2
Move the effort further from the pivot, so the same force produces a larger moment.
3
Move the load closer to the pivot, so the moment of the load is smaller and less effort is needed.
4
When the lever is balanced, the effort multiplied by its distance equals the load multiplied by its distance from the pivot.

Part 4 of 5Worked Example

Question

  • A crowbar is pivoted at a point so that the effort arm is 1.2 m long and the load arm is 0.15 m long.
  • A downward effort of 200 N is applied at the end of the effort arm.
  • Assuming the lever is balanced, calculate the upward force on the rock.

  1. Moment of the effort about the pivot: 200 × 1.2 = 240 N m.
  2. For balance, the moment of the rock's force must also equal 240 N m.
  3. Upward force on the rock × 0.15 = 240 N m.
  4. Upward force = 240 ÷ 0.15 = 1600 N.

Answer The upward force on the rock is 1600 N.

Part 5 of 5Exam Checklist & Tips

1.8.3 – Key Points for the Exam

  • Lever A rigid bar that turns about a pivot to multiply a force.
  • Pivot The fixed point about which a lever turns.
  • Effort The input force applied to a lever.
  • Load The output force that the lever moves or lifts.
  • Force multiplier A device that makes the output force larger than the input force.

Common Mistakes

  • Stating that a lever creates energy; it multiplies the force, but it does not add energy.
  • Measuring the distance from the end of the lever rather than from the pivot.
  • Using the effort force in place of the load force when calculating the force on the load.
  • Confusing the direction of the output force with the direction of the effort.

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