Lecture 1+2
What is Faraday's law about?
. A moving wire in a magnetic field generates electric current
The type of matter we (human beings) are made of constitutes ____ of the universe
0.03
• What is the key question that Newton asked?
Does the law dictating an apple's fall also dictate the motion of the Moon?
Five major areas of physics
Mechanics Thermal physics Electricity and magnetism Quantum physics Relativity
The Sun has been burning for billions of years because
Nuclear forces
• Newton's three laws of motion are
Object in motion stays in motion unless acted on by outside force For every action there is an equal and opposite reaction Force is mass times acceleration
Methodology of Physics
1. Observation - Find something very interesting. Curiosity! 2. Experiment: Measure the observation quantitatively 3. Reasoning: Explain the observation using a model (hypothesis) 4. Theory: Describe the model in simple and beautiful mathematical equations 5. Prediction: Test the theory by new experiments; does it agree? -Yes, good! put the equations in the textbook -No, exciting! go to step 2. You have made a new discovery!
Galileo Galilei
1564-1642, Italian He has been called • the "father of modern observational astronomy" • the "father of modern physics" • and the "father of modern science."
• How did Aristotle explain why an object moves toward the earth?
Because it wants to be united with the earth
Prof. Kaku mentioned many inventions that can be traced to physicists. Which one is NOT mentioned?
Explosives
Maxwell discovered
Light is an electromagnetic wave
According to Prof. Kaku, the history of physics is the history of
Modern civilization
Physics definition
Physics" is from an ancient Greek word φύσις (physis), meaning "nature". • Until around the end of the 19th century, it was called "natural philosophy". • Today, physics is defined as the study of matter and energy and the relationships between them. Physics is, in some senses, the oldest and most basic science. • The other sciences are generally more limited in scope and may be considered branches that have split off (or emerged) from physics.
What happens when matter meets antimatter?
Release energy
The Theory of Everything is NOT about
To explain the origin of life
What was Einstein's unsolved problem when he died?
Unified field theory
What phenomena does E = mc2 explain?
Why do we have energy on Earth? Why does the galaxy light up? Why do the stars shine?
At around the age of 23, Newton
invented calculus
What determines the period of a swing pendulum?
• 1st step: measure its period • 2nd step: what physical properties determine the period of a pendulum? • 3rd step: measure its period against the length, mass, initial angle: "experiment" • 4th step: understand the underlying reason
Galileo's pendulum
• Set up standards of length and time, so that measurements made on different days and in different laboratories could be compared in a reproducible fashion • Recognized that his experimental data would never agree exactly with any theoretical or mathematical form, because of the imprecision of measurement, unavoidable friction, and other factors
The job of physicists is
• To find a few (as few as possible) fundamental laws that govern nature; • To describe these laws in the language of elegant (as beautiful as possible) mathematical equations; • To use these mathematical equations to explain natural phenomena and to make predictions (as many as possible).
Pendulum questions
• What pattern do you find? A regularly elevated motion • How to describe this pattern quantitatively Time span of one swing • What determines the period of a pendulum? Mass, length of string, power
