1 PHYSICS Newton Einstein Lectures for the 1 st year Electronics and Telecommunications

2 Professor : Tadeusz Pisarkiewicz Office in C1 building, Room 304, office hours Thursday 1:00–2:00 PM, Teaching Assistants: Barbara Dziurdzia, Konstanty Marszałek, Textbook: Fundamentals of Physics, parts 1 - 5, D. Halliday, R. Resnick, J. Walker, Wiley & Sons, Inc. Sudent web site Resources

3 prof. Tom Murphy – UCSD: An attempt to rationalize the observed Universe in terms of irreducible basic constituents, interacting via basic forces. –Reductionism! An evolving set of (sometimes contradictory!) organizing principles, theories, that are subjected to experimental tests. This has been going on for a long time.... with considerable success What is “Physics”

4 Attempt to find unifying principles and properties e.g., gravitation: Universal Gravitation “Unification” of forces Kepler’s laws of planetary motion Falling apples Reductionism

5 Many thousands Many hundreds Tens 3 An ongoing attempt to deduce the basic building blocks All the stuff you see around you Chemical compounds Elements (Atoms) e,n,p Superstrings? Reductionism, cont.

6 Fundamental interactions gravitational interactions example: the force that holds the Moon in its orbit and makes an apple fall. Newton’s law of gravitation F - force of interaction between particles with masses m 1 and m 2, r – the distance between particles, G = 6.67 x Nm 2 /kg 2, the gravitational constant. electromagnetic (EM) interactions Basic interactions in everyday life (EM radiation, cohesion, friction, chemical and biological processes, etc.) between electric charges and magnetic moments Coulomb’s law Q 1, Q 2 – point electric charges separated by distance r ε o – permittivity constant, F – static el. force (attractive or repulsive)

7 Fundamental interactions, cont. strong interactions Responsible for binding of nucleons to form nucleus (nuclei) and for nuclear reactions. Short-range interactions (~ m). Simple laws of interaction do not exist. weak interactions Responsible for β decay and for disintegration of many elementary particles. Short-range interactions (~ m), which do not give bound objects. Comparison of interaction intensities InteractionRelative intensity strong1 EM7.3 x weak10 -5 gravit.2 x

8 Vector calculus There are quantities that can be completely described by a number and are known as scalars. Examples: temperature, mass. Other physical parameters require additional information about direction and are known as vectors. Examples: displacement, velocity, force. All vectors in Fig.(a) have the same magnitude and direction. A vector can be shifted without changing its value if its length and direction are not changed. All three paths in (b) correspond to the same displacement vector. Vectors are written in two ways: either by using an arrow above or using boldface print.

9 Vector components Each vector can be resolved into components, e.g. by projection on the axes of a rectangular coordinate system The scalar component is obtained by drawing perpendicularly straight lines from the tail and tip of the vector to the x axis. By using unit vectors (vectors having magnitude of exactly 1 and pointing in a particular direction) one can express vector as

10 Addition of vectors Vectors can be added geometrically or in a component form (using algebraic rules). (a)The tail of is placed at the tip of. The resultant vector connects the tail of and the tip of (polygon method). (b)Vector sum is the diagonal connecting common vectors origin with the opposite corner of a parallelogram (parallelogram method). Geometric addition Agebraic addition

11 Vector subtraction Vectors can be also subtracted geometrically or by components. The subtraction can be reduced to vector addition. Agebraic subtraction x O y Parallelogram method Polygon method

12 The scalar product The scalar product (dot product) of two vectors gives scalar and is defined as follows: (orthogonality criterion: ) The dot product can be considered as the product of the magnitude of one vector and the scalar component of the second vector along the drection of the first vector. Using component notation one obtains for the dot product in three dimentions:

13 The vector product The direction of vector is perpendicular to the plane defined by multiplied vectors and its sense is given by the right-hand rule. The vector product (cross product) of two vectors is a vector, whose magnitude is.

14 The vector product, cont. In terms of vector components one calculates the determinant: The order of two vectors in the cross product is important: