Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

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Performance objectives

• Define circular motion and its characteristics.
• Explain uniform circular motion with examples.
• Describe and calculate centripetal force.
• Understand the relationship between linear and angular quantities.

Lesson summary

Welcome, students! Today, we are moving from the study of motion in a straight line (linear motion) to motion in a curve. Specifically, we will explore circular motion. This is a type of motion we see everywhere around us in Ghana. Think about a car driving around the Tetteh Quarshie Interchange in Accra, the blades of a standing fan cooling a room, or even the moon orbiting the Earth. Understanding the principles of circular motion is essential for explaining these phenomena and for fields like engineering, satellite technology, and even sports.

Lesson notes

A. What is Circular Motion? Circular motion is the movement of an object along the circumference of a circle or rotation along a circular path.

A special and important type is Uniform Circular Motion (UCM). This occurs when an object moves in a circle at a constant speed. Key Misconception Alert: Constant *speed* does not mean constant *velocity*. Speed is a scalar quantity (it only has magnitude, e.g., 20 m/s). Velocity is a vector quantity (it has both magnitude and direction, e.g., 20 m/s *North*).

In UCM, the direction of the object's velocity is continuously changing. At any point on the circle, the velocity vector is tangent to the path. Since the direction is changing, the velocity is changing, and therefore, the object is accelerating.

*(Teacher can draw this on the board: A circle with arrows showing the tangential velocity at different points, all of the same length but pointing in different directions).*

Evaluation guide

• Demonstrate
• knowledge and
• understanding of
• circular motion.