Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Define momentum and impulse.
• Use conservation of momentum for inelastic collisions.
• Apply equations for elastic collisions.
• Relate impulse and momentum to Newton's second law.
• Solve numerical problems.

Lesson summary

This lesson delves into the fundamental concepts of momentum, impulse, and their relationship to force. We see these principles in action all around us in Ghana: a "tro-tro" driver applying brakes suddenly, a footballer heading a ball during a match, or even the impact of a pestle pounding fufu in a mortar. Understanding these concepts is crucial not only for passing Physics examinations but also for appreciating the principles behind road safety, sports engineering, and many everyday interactions. We will build a strong foundation by linking momentum to Newton's laws and then apply this knowledge to understand what happens when objects collide.

Lesson notes

This section breaks down the core ideas you need to master. We will move step-by-step from definitions to complex applications. 2.1 Momentum

Momentum is a measure of the "quantity of motion" an object has. A simple way to think about it is "mass in motion". An object must be moving to have momentum. A stationary Articulator truck has zero momentum, but a small stone thrown at high speed has significant momentum. Definition: Momentum is the product of an object's mass and its velocity. Formula: `p = mv` Where: `p` = momentum `m` = mass `v` = velocity Nature: Momentum is a vector quantity. It has both magnitude and direction, which is the same as the direction of the velocity. S.I. Unit: kilogram-metre per second (kg m/s).

Example: An "okada" rider and his motorcycle have a combined mass of 200 kg and are moving at 15 m/s. Their momentum is: `p = mv = 200 kg * 15 m/s = 3000 kg m/s` 2.2 Impulse

Impulse is the effect of a force acting over a period of time. It is the measure of the overall effect of a force. A small force acting for a long time can produce the same impulse as a large force acting for a short time. Definition: Impulse is the product of the average force acting on an object and the time interval over which the force acts. Formula: `Impulse (I) = F * Δt` Where: `I` = impulse `F` = average force `Δt` = time interval Nature: Impulse is also a vector quantity, with its direction being the same as the direction of the force. S.I. Unit: Newton-second (N s). (Note: 1 N s is equivalent to 1 kg m/s). 2.3 The Link: Impulse-Momentum Theorem (Indicator 3.1.3.AS.1.2)

Evaluation guide

• Use momentum change to establish impulse and hence deduce Newton's second
• law of motion.
• Enquiry learning :
•  Let learners use the principle of conservation of momentum to establish an equation to