Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Apply concepts of Mechanics: Newton's Laws, Work, Energy, and Power.
• Solve quantitative problems using Stoichiometry.
• Calculate pH and solve titration problems for Acids and Bases.
• Solve problems with series and parallel electric circuits.
• Define and explain the photoelectric effect.

Lesson summary

This week marks the beginning of our focused revision and examination preparation for Grade 12 Physical Sciences. This initial week will be dedicated to solidifying your understanding of fundamental concepts that underpin much of the syllabus. A strong grasp of these basics is crucial, just like a solid foundation is essential for a durable building.

Think of it this way: understanding mechanics helps you understand how load-shedding affects generators, or how solar panels are used to generate electricity, impacting South African communities directly.

Lesson notes

2. 1.

Mechanics: Newton's Laws of Motion, Work, Energy, and Power Newton's Laws of Motion: Newton's First Law (Law of Inertia): An object remains at rest or in uniform motion in a straight line unless acted upon by a resultant force. Inertia is the tendency of an object to resist changes in its state of motion.

Newton's Second Law: The net force acting on an object is directly proportional to the rate of change of momentum and takes place in the direction of the force. Mathematically, F net = ma, where F net is the net force, m is the mass, and a is the acceleration.

Newton's Third Law: When object A exerts a force on object B, object B simultaneously exerts an equal and opposite force on object

A. These forces act on different objects. Work, Energy, and Power: Work (W): The energy transferred when a force causes a displacement. W = Fdcosθ, where F is the force, d is the displacement, and θ is the angle between the force and displacement vectors.

Unit: Joule (J)

Energy: The ability to do work.

Kinetic Energy (E k ): The energy of motion. E k = (1/2)mv 2 , where m is the mass and v is the velocity.

Potential Energy (E p ): Stored energy.

Gravitational Potential Energy (E p ): Energy due to an object's height above a reference point. E p = mgh, where m is the mass, g is the acceleration due to gravity (approximately 9.8 m/s 2 ), and h is the height.

Elastic Potential Energy (E p ): Energy stored in a spring when stretched or compressed. E p = (1/2)kx 2 , where k is the spring constant and x is the extension or compression.

Work-Energy Theorem: The net work done on an object equals the change in its kinetic energy. W net = ΔE k = E kf - E ki Power (P): The rate at which work is done. P = W/t, where W is work and t is time. Alternatively, P = Fv, where F is the force and v is the velocity.

Unit: Watt (W)