CSUN PHYSICS WORKSHOPSUMMER 2001July 9 - July 20

Instructors: Dr. Julio Blanco

Dr. Say-Peng Lim

Supported by the California Post-Secondary Education Commission

DIAGNOSTIC TEST

• RELAX! The test is ANONYMOUS.

• Please answer the questions as best you can.

• You have 1 hour.

• Do not write on the question-sheets.

• You should keep a duplicate copy of your answers for your own diagnostic.

PRELIMINARIES

• Explanation of diagnostic test.

• Register for course credit - grades based on workshop participation/final exam.

• Introduction and background of participants - classes taught, calculus?

• HyperNews & homepage introduction.

• Various software for self-learning.

• Textbooks - Active Physics?.

PRELIMINARY SUMMER PROGRAM

Date Topics Content Standards

July 9,10 One-dimensional motion 1-a

Newton's First and Second Laws 1-b, 1-c

Vectors 1-i, 1-j

Experiment - Force Table

July 11,12 Newton's Third Law 1-d

Static Equilibrium 1-h, 1-k

Circular Motion 1-g, 1-l

Gravitation 1-e, 1-f, 1-m, 5-o

Experiment - Free Fall

July 13,16 Work and Energy 2-a to 2-c, 2-h

Linear Momentum 2-d, to 2-h

Experiment - Ballistic Pendulum

July 17,18 Temperature and Kinetic Theory 3-c

Heat 3-a

Thermodynamics - 1st & 2nd Laws 3-d

Experiment - Work & Heat

July 19,20 Heat Engines 3-b, 3-g

Entropy and 2nd Law 3-e, 3-f

Experiment - Heat Engine

Why Study Physics?• It is extremely interesting.

• It is the most fundamental of all the sciences.

• It forces you to think through a problem and develop problem solving skills.

• Learn analytical and modeling skills.

• The ability and faith that you can solve any/complex problems.

• Prepares you well for lifelong learning.

What Students Should Learn• NOT Laws of Physics!• Skills Physicists use in applying these Laws -

transferable to other fields.– Simplification– Idealization– Approximation– Pictorial, Graphical, and Mathematical

Representations of phenomena– Mathematical/Conceptual Modeling

STYLE OF WORKSHOP• Reading Quizzes at the beginning of each topic.• Each topic is divided into several key concepts.• Introduction of Concept.• Test of concept: question posed

individual answer group discussion

revised answer/tally Explanation

Reading Quiz - Kinematics

1. The slope of the curve in the position vs. time graph for a particle’s motion gives

___ 1. the particle’s speed.___ 2. the particle’s acceleration.___ 3. the particle’s average velocity.___ 4. the particle’s instantaneous velocity.___ 5. not covered in the reading assignment

2. Is it possible for an object’s instantaneous velocity and instantaneous acceleration to be of opposite sign at some instant of time?___ 1. yes___ 2. no___ 3. need more information

3. Without air resistance, an object dropped from a plane flying at constant speed in a straight line will

___ 1. quickly lag behind the plane.___ 2. remain vertically under the

plane.___ 3. move ahead of the plane.___ 4. not covered in the reading

assignment

4. A ball is thrown downward (not

dropped) from the top of a tower. After being released, its downward acceleration will be

___ 1. greater than g.___ 2. exactly g.___ 3. smaller than g.___ 4. not covered in the reading

assignment

Kinematics: One-dimension• Importance of a Reference frame - origin

and direction; Cartesian, Polar.

• Distance versus Displacement.

• Speed versus Velocity.

• Average speed:

• Instantaneous speed: limit as

• Graphical representation.

xvt

0t

Quantitative Problems1) An airplane travels 2100 km at a speed of 800

km/h, and then encounters a tailwind that boosts its speed to 1000 km/h for the next 1800 km. What was the total time for the trip? What was the average speed?

2) Calculate the average speed and average velocity of a complete round-trip in which the outgoing 200 km is covered at 90 km/h, followed by a one-hour lunch break, and the return 200 km is covered at 50 km/h.

• Velocity - rate of change of displacement.

• Acceleration - rate of change of velocity.

• Average acceleration:

• Instantaneous acceleration: limit as

• Graphical Representation.

• Constant acceleration motion.

• Why? Easy; acceleration due to gravity

vat

0t

ov v at 212o ox x v t at 22 2 ( )o ov v a x x

29.8 m/sg

Quantitative Problems1) Determine the stopping distance for an

automobile with an initial speed of 25 m/s and human reaction time of 1.0 s for an acceleration of -4.0

2) A car moving at 5 m/s undergoes an acceleration of 3 to a final speed of 20 m/s. What was the time taken? Through what distance did the car move during the third second?

.2m/s

2m/s

Vector Quantities

• Vectors are quantities that have magnitudes and directions; and add like displacement.

• Addition and Subtraction of Vectors.

• Multiplication of Vectors?

• Resolving a Vector into components - Trigonometry and the Pythagorean theorem

Quantitative Problems1) Vector A is 8.08 units long and points along

the negative x-axis. Vector B is 4.51 units long and points at 45 degrees above the positive x-axis. What is the sum of the two?

2) A skier is accelerating down a 30 degree hill at 3.8 meters per second squared. What is the vertical component of her acceleration? If she starts from rest and accelerates uniformly, how long does it take her to reach the bottom of the hill if the elevation change is 335 m?

Projectile Motion

• Refers to the two-dimensional motion under the influence of gravity only.

• Key - resolve motion into independent horizontal and vertical motions; time being the quantity that is common.

• Trajectory that results is a parabola; Range; Maximum height.

Quantitative Problems A rescue plane wants to drop supplies to

isolated mountain climbers on a rocky ridge 245 m below. If the plane is traveling horizontally with a speed of 70 m/s, how far in advance of the recipients (horizontal distance) must the goods be dropped?

If the goods were released 425 m in advance of the climbers,what vertical velocity (up or down) should the supplies be given?