ICSE Class 10 Physics: Machines — Levers, Pulleys & Notes 2026

Introduction to Simple Machines

• Purpose: magnify force or change direction of force
• Key terms: load, effort, fulcrum, mechanical advantage (MA), velocity ratio (VR)
• Ideal machine: MA = VR, efficiency = 100%

Levers — Classes and Examples

• Class I lever: fulcrum between load and effort (see-saw, scissors)
• Class II lever: load between fulcrum and effort (wheelbarrow, bottle opener)
• Class III lever: effort between fulcrum and load (tongs, fishing rod)

Pulleys — Single, Fixed and Movable

• Single fixed pulley: VR=1, changes direction of effort only
• Single movable pulley: VR=2, MA=2 ideally, halves effort
• Block and tackle: VR = number of rope segments supporting the load

Inclined Plane

• VR = length of plane / height; mechanical advantage with friction
• Screw as a modified inclined plane; VR = 2πl/p
• Wedge: double inclined plane used to split materials

Wheel and Axle

• VR = radius of wheel / radius of axle; steering wheel example
• Gears as wheel-and-axle systems; gear ratio calculation
• Winding handle of a well: practical wheel-and-axle application

Efficiency and Energy Loss

• η = useful output energy / total input energy × 100%
• Sources of inefficiency: friction, weight of machine parts, deformation
• How to improve efficiency: lubrication, ball bearings, lightweight components

ICSE Numericals on Machines

• Find effort to lift 240 N load using a system of pulleys with VR=4
• Calculate efficiency if MA=3 and VR=5
• Lever problem: find length of effort arm given MA and load arm