Physics I_Lecture_1_Introduction

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Physics I:

Physics I Dr. Mohammed Mostafa [email protected]

Entry:

Entry Physics, the most fundamental physical science, is concerned with the basic principles of the Universe.

Entry:

Entry It is the foundation upon which the other sciences—astronomy, biology, chemistry, and geology—are based.

What is Physics?:

What is Physics? Physics is a branch of science that involves the study of the physical world: energy, matter, and how they are related.

Beauty of physics:

Beauty of physics The beauty of physics lies in the simplicity of the fundamental physical theories and in the manner in which just a small number of fundamental concepts, equations, and assumptions can alter and expand our view of the world around us.

PowerPoint Presentation:

The study of physics can be divided into six main areas:

Six main areas of Physics:

Six main areas of Physics 1. classical mechanics, which is concerned with the motion of objects that are large relative to atoms and move at speeds much slower than the speed of light; 2. relativity, which is a theory describing objects moving at any speed, even speeds approaching the speed of light; 3. thermodynamics, which deals with heat, work, temperature, and the statistical behavior of systems with large numbers of particles; 4. electromagnetism, which is concerned with electricity, magnetism, and electromagnetic fields; 5. optics, which is the study of the behavior of light and its interaction with materials; 6. quantum mechanics, a collection of theories connecting the behavior of matter at the submicroscopic level to macroscopic observations.

Six main areas of Physics:

Six main areas of Physics 1. Classical Mechanics, which is concerned with the motion of objects that are large relative to atoms and move at speeds much slower than the speed of light;

Six main areas of Physics:

Six main areas of Physics 2. Relativity, which is a theory describing objects moving at any speed, even speeds approaching the speed of light;

Six main areas of Physics:

Six main areas of Physics 3. Thermodynamics, which deals with heat, work, temperature, and the statistical behavior of systems with large numbers of particles;

Six main areas of Physics:

Six main areas of Physics 4. Electromagnetism, which is concerned with electricity, magnetism, and electromagnetic fields;

Six main areas of Physics:

Six main areas of Physics 5. Optics, which is the study of the behavior of light and its interaction with materials;

Six main areas of Physics:

Six main areas of Physics 6. Quantum Mechanics, a collection of theories connecting the behavior of matter at the submicroscopic level to macroscopic observations.

Mathematics in Physics:

Mathematics in Physics Physics uses mathematics as a powerful language.

Mathematics in Physics:

Mathematics in Physics In physics, equations are important tools for modeling observations and for making predictions.

Mathematics in Physics:

Mathematics in Physics Physicists rely on theories and experiments with numerical results to support their conclusions.

Mathematics in Physics:

Mathematics in Physics For example, think back to the Launch Lab. You can predict that if you drop a penny, it will fall.

Mathematics in Physics:

Mathematics in Physics But how fast? Different models of falling objects give different answers to how the speed of the object changes, or on what the speed depends, or which objects will fall.

Mathematics in Physics:

Mathematics in Physics By measuring how an object falls, you can compare the experimental data with the results predicted by different models. This tests the models, allowing you to pick the best one, or to develop a new model.

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Length (m): In October 1983, the meter (m) was redefined as the distance traveled by light in vacuum during a time of 1/299 792 458 second.

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Length of a football field: 9.1 x 10^1 (m)

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Mean distance from the Earth to the Moon: 3.84 x 10^8 (m)

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Mass(Kg): The kilogram (kg), is defined as the mass of a specific platinum–iridium alloy cylinder kept at the International Bureau of Weights and Measures at Sèvres, France.

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Masse of Sun: 1.99 x 10^30 (Kg)

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Masse of Electron : Electron 9.11 x 10^31 (Kg)

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Time (s): The second (s) is now defined as 9 192 631 770 times the period of vibration of radiation from the cesium atom.

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units Age of the Universe: 5 x 10^17 (s)

Standards of Length, Mass, and Time - SI units:

Standards of Length, Mass, and Time - SI units One year: 3.2 x 10^7 (s)

Prefixes for Powers of Ten:

Prefixes for Powers of Ten

Matter and Model Building:

Matter and Model Building If physicists cannot interact with some phenomenon directly, they often imagine a model for a physical system that is related to the phenomenon.

Matter and Model Building:

Matter and Model Building Why ? Once we have identified the physical components, we make predictions about the behavior of the system, based on the interactions among the components of the system and/or the interaction between the system and the environment outside the system

Dimensional Analysis:

Dimensional Analysis The word dimension has a special meaning in physics. It denotes the physical nature of a quantity

Dimensional Analysis:

Dimensional Analysis Whether a distance is measured in units of feet or meters or fathoms, it is still a distance. We say its dimension is length

Dimensional Analysis:

Dimensional Analysis We shall often use brackets [ ] to denote the dimensions of a physical quantity.

Dimensional Analysis:

Dimensional Analysis For example, the symbol we use for speed is v, and in our notation the dimensions of speed are written [ v] = L / T.

Dimensional Analysis:

Dimensional Analysis As another example, the dimensions of area A are [A] = L^2.

Dimensional Analysis:

Dimensional Analysis The dimensions and units of area, volume, speed, and acceleration are listed in this Table:

Dimensional Analysis:

Dimensional Analysis Dimensions can be treated as algebraic quantities. you can use dimensional analysis to help determine whether an expression has the correct form.

Dimensional Analysis:

Dimensional Analysis Let us use dimensional analysis to check the validity of this expression x = ½ a t^2 . The quantity x on the left side has the dimension of length. For the equation to be dimensionally correct, the quantity on the right side must also have the dimension of length L.

Dimensional Analysis:

Dimensional Analysis We can perform a dimensional check by substituting the dimensions for acceleration, L/T^2 and time, T, into the equation, That is, the dimensional form of the equation is;

Dimensional Analysis:

Dimensional Analysis Show that the expression v = a.t is dimensionally correct where v represents speed, a acceleration, and t an instant of time. [v]=[at]

Dimensional Analysis:

Dimensional Analysis Suppose we are told that the acceleration a of a particle moving with uniform speed v in a circle of radius r is proportional to some power of r, say r n , and some power of v, say v m .

Dimensional Analysis:

Dimensional Analysis Suppose we are told that the acceleration a of a particle moving with uniform speed v in a circle of radius r is proportional to some power of r, say r n , and some power of v, say v m . Determine the values of n and m and write the simplest form of an equation for the acceleration .

Dimensional Analysis:

Dimensional Analysis Suppose we are told that the acceleration a of a particle moving with uniform speed v in a circle of radius r is proportional to some power of r, say r n , and some power of v, say v m . Determine the values of n and m and write the simplest form of an equation for the acceleration .