SCIENCE REVIEWER! REVIEWER ! CHAPTER 1 Physics – Comes from the Greek word physike, word physike, meaning “nature” Concerned with the fundamental laws of na ture, this is why physics was once called natural philosophy and philosophy and also referred to as the pioneer science. science . It [Physics] is defined as the study of matter and energy and their interactions. It’s divided into classical (Events, etc prior to 1900] and modern [Events, etc after 1900] physics. There are different branches of physics:
Mechanics – The oldest branch of physics, which deals with ideas like inertia, forces, motion, energy and properties of matter. Heat – Heat – Deals with temperature measurement, effects of heat and methods of heat transfer. Thermodynamics – Study of activities involving heat and work. Optics – Study of light and its properties. Sound – Covers vibrations and waves and their properties, transmission, and perception as in music/speech. Electricity and Magnetism – Deals with the nature of charge, cha rge, the phenomena associated with charged particles a t rest and in motion, effects of electric current and phenomena associated with magnetism. Classical Physics – Deals with objects that are neither too large nor too small and that move with speeds very small compared to the speed of light in a vacuum. Modern Physics – Deals with X-rays, nuclear physics a nd radioactivity, atomic physics, particle physics, theory of relativity, etc. Special Relativity – Deals with objects moving at a speed very close to the speed of light in a vacuum, app. 3 x 10 8 m/s
The year 2005 was declared as the World Year of Physics by The International Union of Pure and Applied Physics and also as the International Year of Physics by UN. Coincided with the 100 th anniversary of Einstein’s Annus Mirabilis (miraculous year), when Einstein published papers that revolutionized physics. Technology – Comes from the Greek words teckne meaning “art of craft”, and logos, meaning articulate speech or discourse”. process…” Technology United Nations Educational, Scientific, and Cultural Org. defines technology as “know -how and creative process…” might be considered as the offspring of physics. Physics deals with the understanding of the natural world while technology aims to apply this understanding. Physics and technology gave us the following:
LASER – light amplification stimulated by emission of radiation, a therapy for cancer, repairing eye or stomach damage. MRI – magnetic resonance imaging, helps view the internal body structure like the brain, to detect tumors or internal injuries. Microscope – to help us view minute organisms invisible to the naked eye. Ultrasound – used to shatter kidney stones, used to detect tumors or cysts and pregnancy probs. Radiation – a way to kill cancer cells to prolong life.
Fundamental quantities – Includes length, mass, time, temperature, electric current, luminous intensity and amount of substance. Derived quantities – Combinations of fundamental quantities. Ex: acceleration, density, work and energy. Lord Kelvin [William Thomson], a British physicist, and Plato, a Greek philosopher, emphasizes the importance of measurement. Measurement – Measurement – Physics begins with it. It’s simply a comparison of a physical quantity with the standard. Metric System has two variations – mks [meter, kilogram, second] and cgs [centimeter, gram, second] system. English system is known as the fps [foot, pound, second] system. International System of Units – abbreviated SI from the French Le Systeme International d’Units is a modern form of the metric system. Dimension – Refers to the physical nature of a quantity and the type o f unit to specify it. It can be treated like algebraic expressions. Dimensional Analysis – Can be used to check whether an expression has the correct form. REMEMBER: Mathematics is the language of physics.
Some formulas to remember: A + B + C = 180 o ; a2 + b2 = c2 LAW OF COSINES: a 2 = b2 + c2 – 2bc (cos A). Used if two sides and their included angle are given. LAW OF SINES: a/sinA = b/sinB = c/sinC SIGNIFICANT FIGURES [digits known with certainty]:
All nonzero digits are significant. Zeros between two nonzero digits are significant. Zeroes to the left of the first nonzero digit are not significant. If a number is greater than one, all zeroes to the right of the decimal point are significant. If a number is less than one, only the zeroes at the end of the number and the zeroes between two nonzero digits are significant. Zeroes to the left of an unexpressed decimal point are not significant.
CHAPTER 2 Scalar Quantities – Scalar comes from the Latin word scala, meaning steps or ladder. Described by their magnitudes and appropriate units. Ex: mass, temperature, speed, time, work, energy and distance. Vector Quantities – Vector comes from the word vehere, meaning to carry. Described by their magnitudes, app. units, & directions. Ex: force, displacement, velocity, acceleration, momentum & torque. VECTORS:
An arrow represents a vector quantity. Symbol for a vector quantity is a capital letter in boldface. The sum of two or more vector quantities is a resultant. Two important properties of vector addition: commutative & associative Two general ways by which vectors may be added: analytical & graphical Graphical method is divided into polygon and parallelogram method. Analytical method is divided into sine and cosine law.
SPECIAL CASES:
For two vectors acting in the same direction – The angle between the two vectors is zero, the magnitude is equal to the sum of the magnitudes of the vectors, the direction is the same as the vectors. For two vectors acting in opposite directions – The angle between the two vectors is 180 o, the magnitude is the difference of the two magnitudes of the vector, direction is the greater vector. For twi vectors perpendicular to each other – The magnitude can be obtained by the Pythagorean Theorem, the direction can be found by using the trigonometric function of a right triangle.