Education Always

Level: JHS, Basic 7  |  Subject: Integrated Science  |  Strand: Forces and Energy  |  Topic: Simple Machines

Curriculum reference: B7.4.4.2 (NaCCA Integrated Science).

1. What is a Machine?

• A machine is a device that makes work easier. It can reduce the effort needed, change the direction of a force, or make work faster.
• A machine does not create energy. It only helps us use our force better.
• Load is the weight to be moved. Effort is the force we apply.

2. Types of Simple Machines

Machine	Example
Lever	See-saw, wheelbarrow, scissors, pliers, crowbar
Pulley	Well rope pulley, crane, flagpole
Inclined plane (ramp)	Ramp for loading a truck, sloping road
Wedge	Axe, knife, nail
Screw	Bolt, jar lid, G-clamp
Wheel and axle	Steering wheel, door knob, bicycle wheel

3. Levers

• A lever is a rigid bar that turns about a fixed point called the fulcrum (pivot).
• First class lever: fulcrum is between the effort and the load. Examples: see-saw, scissors, crowbar.
• Second class lever: load is between the fulcrum and the effort. Examples: wheelbarrow, nutcracker, bottle opener.
• Third class lever: effort is between the fulcrum and the load. Examples: fishing rod, tweezers, a broom being swept.

4. Mechanical Advantage, Velocity Ratio and Efficiency

• Mechanical advantage (MA) = load ÷ effort. It has no unit.
• Velocity ratio (VR) = distance moved by effort ÷ distance moved by load.
• Efficiency = (MA ÷ VR) × 100%.
• Example: a load of 600 N is lifted with an effort of 200 N. MA = 600 ÷ 200 = 3.
• No machine is 100% efficient because of friction.

5. Uses in Ghana

• Wheelbarrows on farms and building sites.
• Pulleys for drawing water from wells.
• Ramps for loading goods onto trucks.
• Cutlass and axe (wedges) for farming.

Remember: A machine makes work easier but does not give extra energy. MA = load ÷ effort. A lever turns on a fulcrum.

Education Always (education.inspiringalways.com). Original notes written to follow the NaCCA Basic 7 Integrated Science curriculum.