Lesson Notes By Weeks and Term v4 - JHS 2

Lesson Video

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Performance objectives

• Explain Newton’s Second Law of Motion with everyday examples.
• Describe the relationship between magnetic force and motion.
• Conduct an experiment to show how magnetic forces affect motion.
• Analyze real-life situations where force and motion are applied.
• Solve problems related to force and motion.

Lesson summary

In our daily lives in Ghana, we see motion everywhere: a trolley being pushed in a market, a bicycle accelerating on a road, a fan pulling iron filings, and a magnet picking nails in a workshop. These situations involve forces causing objects to speed up, slow down, or change direction. In this lesson, learners will use magnetic force to investigate the relationship between force and motion and connect it to Newton’s Second Law of Motion.

Lesson notes

2.1 Force and Motion (Meaning) Force: A push or pull that can change an object’s motion (speed or direction) or shape. Unit: Newton (N) Motion: Change in position with time. Speed: How fast an object moves (distance/time). Velocity: Speed in a particular direction. Acceleration: How quickly velocity changes (speeding up, slowing down, or changing direction). Unit: m/s² 2.2 Newton’s Second Law of Motion Newton’s Second Law says:

> The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

In formula form: \[ F = ma \] Where: \(F\) = net force (N) \(m\) = mass (kg) \(a\) = acceleration (m/s²) Key relationships from \(F = ma\) If mass stays the same: \[ a \propto F \] Increasing force increases acceleration. If force stays the same: \[ a \propto \frac{1}{m} \] Increasing mass decreases acceleration. 2.3 Magnetic Force as a Type of Force Magnetic force is a non-contact force (it acts without touching). A magnet can attract magnetic materials like iron, steel, cobalt, nickel. Magnetic force can cause an object to move, speed up, slow down, or change direction—so it can be used to study force and motion. 2.4 Using Magnetic Force to Demonstrate Newton’s Second Law We can set up an experiment where: A magnet pulls a small metal object (or a paper clip) attached to a toy trolley or cart. By changing the strength of the magnetic pull, we change the force. By adding loads (coins, stones, metal washers) to the trolley, we change the mass. How to change magnetic force in a simple classroom Move the magnet closer → stronger pull (greater force). Move the magnet farther → weaker pull (smaller force). Use two magnets instead of one → stronger pull. 2.5 Worked Examples (Ghanaian context) Example 1: Same mass, different force A small trolley has mass \(m = 0.5\,kg\).

Case A: Magnetic pull \(F = 1.0\,N\) \[ a = \frac{F}{m} = \frac{1.0}{0.5} = 2.0\,m/s^2 \]

Evaluation guide

• Explain Newton’s Second Law of motion with examples from daily life.
• Perform an experiment to show the relationship between force and
• motion using magnetic force, and the principle of Newton’s Second
• Law of Motion. Critical Thinking and Problem Solving