Grade 9 Physics unit 1: Physics and Human Society

According to the textbook, the word physics comes from the Greek word phusis, which means nature.

Acoustics is the branch of physics that studies sound, including its transmission, production, and effects.

Optics is the branch of physics that deals with the behavior, propagation, and properties of light.

Galileo Galilei was the first scientist to study the solar system and the universe using a telescope.

Mechanics is divided into classical mechanics and quantum mechanics. Quantum mechanics deals with the behavior of the smallest particles like electrons, protons, and neutrons.

Medical physics applies physics principles to medical diagnostics and therapies, including X-rays, MRI, and ultrasound.

Michael Faraday made major contributions to electromagnetism, including the discovery of electromagnetic induction, diamagnetism, and electrolysis.

Joule studied the relationship between heat and mechanical work, which led to the law of conservation of energy and laid the foundation for the first law of thermodynamics.

Physics as it developed from the Renaissance to the end of the 19th century is called classical physics. Modern physics began with revolutionary discoveries at the start of the 20th century.

Geology relies heavily on physics for methods such as radioactive dating, earthquake analysis, and heat transfer across Earth's surface.