170 likes | 286 Views
College Physics. Chapter 1 Introduction. Science is a Philosophy. It is not science without data It is not science without measurement errors (somehow) It is not science unless it can be reproduced (objectivity) Math is like the grammar of science.
E N D
College Physics Chapter 1 Introduction
Science is a Philosophy • It is not science without data • It is not science without measurement errors (somehow) • It is not science unless it can be reproduced (objectivity) • Math is like the grammar of science
Fundamental Quantities and Their Dimension • Length [L] • Mass [M] • Time [T] • other physical quantities can be constructed from these three
Systems of Measurement • Standardized systems • agreed upon by some authority • SI -- Systéme International • 1960 by international committee • main system used in this text • also called “mks” units • cgs – Gaussian system • US Customary • nits of common usage
Prefixes • Metric prefixes correspond to powers of 10 • Each prefix has a specific name • Each prefix has a specific abbreviation • See table 1.4
Dimensional Analysis • Technique to check the correctness of an equation • Dimensions (length, mass, time, combinations) can be treated as algebraic quantities • add, subtract, multiply, divide • Both sides of equation must have the same dimensions
Uncertainty in Measurements • There is uncertainty in every measurement, and uncertainty carries over through calculations • Lab uses rules for significant figures to approximate the uncertainty in calculations
Conversions • Units must be consistent (time=time) • Units carry value! (1 m = 100 cm) • You can manipulate words in equations just like you manipulate numbers • Example:
Cartesian coordinate system • Also called rectangular coordinate system • x- and y- axes • Points are labeled (x,y)
Plane polar coordinate system • Origin and reference line are noted • Points labeled (r,q) • Point is distance r from the origin in the direction of angle , (counterclockwise from reference line)
More Trig • Pythagorean Theorem • To find an angle, you need the inverse trig function • for example, • Be sure your calculator is set appropriately for degrees or radians • Must beware of quadrant ambiguities
Polar Coordinates Example • Convert the Cartesian coordinates for (x,y) to Polar coordinates (r,q)
How High Is the Building? • Determine the height of the building and the distance traveled by the light beam