Lesson Notes By Weeks and Term v4 - JHS 3

Lesson Video

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Performance objectives

• Predict what happens when a force is exerted on an object.
• Explain the relationship between action and reaction forces.
• Demonstrate how forces affect the motion of objects.
• Identify real-life examples of forces and motion.
• Calculate force, mass, and acceleration.

Lesson summary

Force and motion explain why objects start moving, stop, speed up, slow down, or change direction. In Ghana, learners meet these ideas every day: pushing a wheelbarrow at the farm, kicking a football, riding a bicycle, pulling a bucket from a well, or feeling a “kick-back” when pushing against a wall. This lesson focuses on Newton’s laws of motion, especially action and reaction (Newton’s 3rd law), and how to predict outcomes and justify predictions through practical activities.

Lesson notes

2.1 Meaning of Force A force is a push or pull that can: start motion or stop motion, increase speed or decrease speed, change direction, change shape (deform).

Unit of force: Newton (N)

Examples (Ghanaian context): Pushing a broken-down “trotro” (push force). Pulling a bucket from a well (pull force). Kicking a football (push force on the ball). Stretching a rubber band (force causes deformation).

2.2 Balanced and Unbalanced Forces Balanced forces: net force = 0 N → no change in motion (object stays at rest or continues at constant speed in a straight line). Unbalanced forces: net force ≠ 0 N → motion changes (acceleration occurs).

Evaluation guide

• Predict what happens when:
• a) a force is exerted on an object.
• b) There is a reaction from the object
• c) the force exerted is the same as the reaction of the object.