Wheel and Axle

• Wheel and axle turn together — a rod through a wheel centre.
• Makes movement easier — less friction than dragging.
• Examples: bicycle wheels, cart, doorknob.
• Transport links in Looking Around 3 — carts and cycles.

Level 1 — Core idea

Verbal: Turn a doorknob (wheel) — the axle inside rotates and opens the latch.

Symbolic: Large wheel + smaller axle = mechanical advantage turning.

Visual: Cart: two big wheels on one axle; push cart rolls smoothly.

Level 2 — Going deeper

Rolling reduces friction compared to sliding the same load. That is why luggage has wheels.

NCERT anchor

NCERT Looking Around 3, Chapter 11 (From Here to There) discusses travel. Compare pushing a box vs pulling it on wheels.

Why do carts have wheels instead of flat sliders?

Step 1 — Sliding = high **friction**
Step 2 — Rolling wheels = less friction
Step 3 — Same pull moves cart **easier** ✓

Doorknob — which is wheel, which is axle?

Step 1 — Round knob you turn = **wheel**
Step 2 — Rod through door connecting latch = **axle**
Step 3 — Both rotate together ✓

• Name two wheel-and-axle examples.
• Why do bicycles have wheels?
• What is an axle?
• Stretch: Suitcase with wheels — which simple machine helps at the airport?

Revision tip: Spot wheels on the way to school — bus, cycle, cart — name the machine.

Open the Practice tab for graded questions on Wheel and Axle.