Mathematics · Class 4
Carts and Wheels
Learn Carts and Wheels with notes, examples, and practice questions.
3 sections15–25 min read3 MCQs · 1 examples
Chapter Overview
Every point on a circle is the same distance from its centre; that distance is the radius.
Carts and Wheels explores circles through wheels, round objects, and drawing activities. Learners identify the centre, radius, and diameter and use a compass to construct circles.
Parts of a Circle
- The centre is the fixed point in the middle.
- A radius joins the centre to the circle.
- A diameter passes through the centre and joins two points on the circle.
- The diameter is twice the radius.
Drawing and Using Circles
- A compass keeps a fixed radius while turning around the centre.
- A larger radius makes a larger circle.
- Wheels roll smoothly because their boundary stays equally far from the axle.
- Not every curved closed shape is a circle.
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Find the Diameter
A wheel has a radius of 9 cm. What is its diameter?
- 1Diameter is twice the radius.
- 2Calculate 2 × 9 cm.
- 3Keep the unit centimetres.
Answer
18 cm
Key Points to Remember
- ✓ A circle has one centre
- ✓ All radii of one circle are equal
- ✓ Diameter = 2 × radius
- ✓ A compass draws a circle with fixed radius
Exam Tips
- • Check that a diameter passes through the centre
- • Do not confuse radius with diameter
- • Keep the compass opening unchanged while drawing
Practice MCQs — Carts and Wheels
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Question 1 of 3Score: 0/0
What joins the centre to a point on the circle?