# phys 150 physics i prerequisite: math 131 calculus i corequisite: phys 150l (lab) instructor: dr....

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PHYS 150 Physics I Prerequisite: MATH 131 Calculus I Corequisite: PHYS 150L (lab)Instructor: Dr. Johnny B. Holmestitle:Professor of Physicsoffice:CW 103phone:321-3448e-mail:jholmes@cbu.eduhomepage: facstaff.cbu.edu/~jholmes/

PHYS 150: Physics IA beginning course in physics covering the topics of kinematics, dynamics, gravitation, work, energy, momentum, rotational kinematics and dynamics.Prerequisites: algebra and basic trig, definition of derivative and integral, ability to differentiate and integrate power laws, sines and cosines.Corequisite: PHYS 150 L (the lab)Can substitute for PHYS 201 Introductory Physics I

Grading: (explained on syllabus)4 tests, each counts as one grade1 set of 9 regular collected homework problems which counts as one grade2 sets of 10 computer homework programs where each set counts as one gradefinal exam, which counts as 3 gradesTotal: 10 grades, final grade will be based on the average of these 10 grades.100 A 93 B 82 C 70 D 65 F - 0

Absence policyIf you miss 3 or fewer classes, your lowest single score will be dropped (not counting homework scores). If the final is lowest, it will count only 2 instead of 3 times. Thus, if you have 3 or fewer class absences, the total will be based on the remaining 9 grades.

Regular HomeworkThere are 9 regular collected homework problems for the semester. These must be done and written up using the 7 step paradigm described in the syllabus. This paradigm is not good for the problems with obvious solutions, but is good for those problems that do not have obvious solutions. It is also a good way of communicating your thinking.

7-step problem solving paradigmI want to and I can (motivation)What do you know (draw a diagram!)What are you looking for (define symbols)Brainstorm (how is what you are looking for related to what you know; what laws apply)Plan the solutionExecute the solution (be sure to include units)Check your answer is it reasonable?

Computer HomeworkThe 20 computer homework programs (each program consists of a problem set) are designed to give you graded practice. They emphasize getting the answer right the first time. If you get an answer wrong, the computer will tell you right away, and often tell you how to get it right. It is your task to actually get them correct. A random number generator will change the numbers so you will have to learn how to do them and not just remember the right answer.

TestsThe 4 tests and final exam emphasize familiarity, recognition and speed. The material on the tests should be somewhat familiar. You should be able to recognize the type of problem, the basic principles involved, and determine which techniques to apply.

Study sheetThis course emphasizes basic principles and problem solving, not memorization.To reduce the perceived need to memorize, you are permitted to bring to the tests one 8.5 x 11 sheet of paper with information on one side. You may bring two study sheets to the final (writing on one side only).

Math ReviewThe first several computer homework problem sets are reviews of the basic algebra that we will use in this course. Included in this review are relations, linear equations, simultaneous equations, and quadratic equations. The first regular collected homework involves a review of angles and basic trigonometry.

Math Review #1:Linear EquationsReview: One Linear Equation:ax + dy = c (we know a, d, and c; we dont know x and y)This is one equation in two unknowns. There are lots of correct answers to this. Example:5x + 3y = 35. Several possible answers are:(x=4, y=5), (x=7, y=0), (x=-5, y=20).

ax + dy = c can be written in the normal formy = mx + b where m = -a/d and b = +c/d.Thus the equation 5x + 3y = 35 becomesy = (-5/3)x + (35/3) y

Every point onthis line satisfiesthe equation(x=4, y=5), (x=7, y=0), (x=-5, y=20). Review: One Equation:-55-1010x

Math Review #2:Simultaneous EquationsHowever, if we have two equations with two unknowns, then there is usually just one possible answer: Example:5x + 3y = 35 AND 2x - y = 3 .In this case, we can solve for one unknown (say y) in terms of x:y = 2x - 3 (using the second equation).

Math Review #2:Simultaneous Equations5x + 3y = 35 AND 2x - y = 3 .Using this relation for y: y = 2x - 3 in the other (first) equation yields:5x + 3(2x - 3) = 35 , or5x + 6x - 9 = 35, or 11x = 44, orx = 44/11 = 4 = x. Now we can use this value for x in the y = 2x - 3 to gety = 2(4) - 3 = 5 = y.

Math Review5x + 3y = 35 AND 2x - y = 3 .Check of our answer: (x=4, y=5) 5x + 3y = 35, or 5(4) + 3(5) = 35, or 20+15 = 35 which checks out. 2x - y = 3, or 2(4) -5 = 3, or 8 - 5 = 3 which also checks out. Hence we have our solution.

Math Review #2:Simultaneous Equations5x + 3y = 35 AND 2x - y = 3 .Graphically, each equation graphs as a straight line, and the y single solution (in our case, x=4, y=5) is the intersection of the two linesx-55-1010

Math ReviewThe computer homework program on Simultaneous Equations has up to three equations with three unknowns. You can proceed the same way. 1. Use one equation to eliminate one of the three unknowns in the other two equations. 2. Then use one of these two equations to eliminate a second unknown from the last equation. 3. Then use the last equation to solve for the remaining one unknown.

Math Review #3a: AnglesBecause space is three dimensional (well talk about this soon), we need angles.What is an angle?

How do you measure an angle?

Math Review #3a: AnglesHow do you measure an angle?1) in circles (cycles, rotations, revolutions)2) in degrees - but what is a degree?Why do they break the circle into 360 equal degrees?3) in radians - but why use a weird number like 2p for a circle? Why does p have the weird value of 3.1415926535 ?

Math Review #3a: AnglesFull circle = 360o (Comes from year - full cycle of seasons is broken into 365 days; but 365 is awkward number; use nicer number of 360.)Full circle = 2p radians (Comes from definition of angle measured in radians: q = arclength / radius = s / r )rsq

Math Review #4: TrigThe trig functions are based on a right triangle:sin() = opposite/hypotenuse = y/rcos() = adjacent/hypotenuse = x/rtan() = opposite/adjacent = y/x(The hypotenuse is the side opposite the right angle.) r yx

What is Physics?First of all, Physics is a Science. So our first question should be: What is a Science?

ScienceWhat is a science?Physics is a science. Biology is a science.Is Psychology a science?Is Political Science a science?Is English a science?What makes a field of inquiry into a science?

Scientific MethodWhat makes a field of inquiry into a science?Any field that employs the scientific method can be called a science.So what is the Scientific Method?What are the steps to this method?

Scientific Method1. Define the problem: what are you studying?2. Gather information (data). This should be repeatable (reproducible) by anyone else with the proper equipment.3. Hypothesize (try to make sense of the data by trying to guess why it works or what law it seems to obey). This hypothesis should suggest how other things should work. So this leads to the need to:4. TEST, but this is really gathering more information (really, back to step 2).

Scientific MethodIs the scientific method really a never ending loop, or do we ever reach the TRUTH ?Consider: can we observe or measure perfectly? If not, then since observations are not perfect, can we perfectly test our theories? If not, can we ever be CERTAIN that weve reached the whole TRUTH ?

Scientific MethodIf we cant get to THE TRUTH, then why do it at all?We can make better and better observations, so we should be able to know that we are getting closer and closer to THE TRUTH. Is it possible to get close enough?Look at our applications (engineering): is our current understanding good enough to make air conditioners?

PhysicsNow Physics is a science, but so are Chemistry and Biology. How does Physics differ from these others?It differs in the first step of the method: what it studies. Physics tries to find out how things work at the most basic level. This entails looking at: space, time, motion (how location in space changes with time), forces (causes of motion), and the concept of energy.

Metric SystemSince physics is a science, and science deals with observations, physics deals with MEASUREMENTS.How do we MEASURE? What do we use as the standard for our measurements?In this course we will look at common units of measurement as well as the METRIC units of measurement.

Metric System:Basic quantitiesSome measurements are basic, and some are combinations of other more basic ones:What are the basics: (MKS system)length (in Meters)amount of stuff called mass (in Kilograms)time (in Seconds)What are some of the combinations:speed (distance per time)area (distance times another distance)lots of other things

PrefixesThe metric unit for length is the meter. We can indicate a multiple of meters or a fraction of a meter by using prefixes:centi (cm) = .01 meters = 10-2 mmilli (mm) = .001 meters = 10-3 mmicro (m) = .000001 meters = 10-6 mnano (nm) = .000000001 meters = 10-9 mpico (pm) = .000000000001 meters = 10-12 m

Prefixes cont.(The prefixes on this page will not be used in this course, but you may run into them in future courses.)femto:(fg) = 10-15 gramsatto:(ag) = 10-18 gramszepto(zg) = 10-21 gramsyocto(yg) = 10-24 grams

PrefixesFor bigger values we have

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