SMILE2340
  • HW 78620
    • Stargazers >
      • Next Night Observation Notes >
        • March 3, 2023 Notes
        • March 10, 2023 Notes
        • March 17, 2023 to be added
      • Frequently Asked Questions >
        • How do you set up your night sky observation sessions?
        • Explain why there are four sunrises/sunsets?
        • What are the fundamental motions of the night sky?
        • Explain magnitude of night sky objects?
        • What is a constellation?
        • Star Enlightenment
        • Moon Enlightenment
        • Have you ever gone into space, Mr. Konichek?
        • Do you have some Earth orbiting the sun stories?
        • Woman's image on Moon?
      • Aniruddh Nayak's Photos
      • Paul's 12" Telescope Photos
      • Kinesthetics >
        • Planets PM or AM h-above
        • Earth/Sun & times of day
        • Moon Proof that it spins on axis
        • Earth / Moon perigee & apogee
        • Sun / Earth Seasons, Zodiac Sign
      • Activities - Hands On >
        • Celestial Sphere with fruit
        • Constellation Puzzles - h-above
        • Outdoor solar system walk
        • Bugs Bunny What's Up Doc
        • Stars on Ceiling Kit
        • 13 constellations on the ecliptic?
    • Field Camera Critters >
      • bobcat
      • Porcupine
      • Two different at same time
      • Coyotes
      • Fox
      • Skunk
      • Racoons
      • Deer
      • Other
  • PHYSICS
    • Year Round Physics Pages >
      • Calendars 2013-2014 >
        • Calendars 2012-2013
      • Physics Textbooks Online
      • How to do a Lab Report
      • How to Graph in Excel
      • GNATS >
        • Infinities
    • Vectortines & Astrotines Day Video - Normal Pre-school morning
    • Physics 1st Quarter 2012-2013 >
      • Unit 1 Motion (1st half) >
        • Sept. 3 Welcome & Intro
        • Sept. 4 Bernoulli >
          • 2013-14 videos
        • Sept 5 Intro to Motion
        • Sept. 6 GREAT RACE
        • Sept. 9 Review Great Race
        • Sept. 10 Physics 500
        • Sept. 11 Graph Your Route
        • Sept. 12 Measurement Lab-Day 1
        • Sept. 13 Measurement Lab-Day 2
        • Sept. 16 Sonic Ranger-Day 1
        • Sept. 17 Acceleration
      • Unit 1 Motion (2nd half) >
        • Sept. 18 Sketch-A-Graph
        • Sept. 19 Fab Five
        • Sept. 20 Rocket Lab
        • Sept. 23 Homework Gravity
        • Sept. 24 Law of Falling Bodies
        • Sept. 25 Freefall Terminal Velocity
        • Sept. 26 Parachutes
        • Sept. 27 Parachute Competition
        • Sept. 30 Review
        • Oct. 1 TEST
        • Oct. 2 Review Awards
      • Unit 2 Acceleration (1st half) >
        • Oct. 3 Factors of Acceleration Lab-Day 1
        • Oct. 4 Factors of Acceleration Lab-Day 2
        • Oct. 7 Donatello, B & B Lab, Prob.
        • Oct. 8 Who Pushed That Speeding Truck? Lab
        • Oct. 9 Inertia Homework
        • Oct. 10 Push That Cart Lab
        • Oct. 11 Push That Cart Lab-Day 2
      • Unit 2 Acceleration (2nd half) >
        • Oct. 14 Tablecloth Videos, Inertia
        • Oct. 15 Friction is Fun Lab-Day 1
        • Oct. 16 Friction is Fun Lab-Day 2
        • Oct. 17 Friction Theories
        • Oct. 18 2013 Hovercraft
        • Oct. 18 2012 Hovercraft 1,2,4,5
        • Oct. 18 2012 Hovercraft 5,7,8
        • Oct. 21 Review
        • Oct. 22 TEST
      • Unit 3 >
        • Oct. 23 Infinities (GNATS2)
        • Oct. 24 Page 1 Action-Reaction
        • Oct. 24 Page 2
        • Oct. 25 Action-Reaction
        • Oct. 28 Vectors- Where Am I?
        • Oct. 29 Addition of Vectors Lab-Day 1
        • Oct. 30 Addition of Vectors Lab-Day 2
        • Oct. 31 Vector Homework
        • Nov. 1 Resolution of a Force Lab
    • Physics 2nd Q >
      • Unit 3 Continued >
        • Nov. 4 Plane Application
        • Nov. 5 Ship application
        • Nov. 6 Weight of the World Lab
        • Nov. 7 Parking on a Hill Lab
        • Nov 8 Vector Bowling 2013 >
          • Nov. 8 Vector Bowling 2012
        • Nov. 12 Fundamental Forces
        • Nov. 13 Review
        • Nov. 14 TEST
      • Unit 4 >
        • Nov. 18 Bull's Eye Lab
        • Nov. 19 Projectile Hunter
        • Nov. 21 Trajectory Lab-Day 1
        • Nov. 22 Trajectory Lab-Day 2
        • Nov. 23 Hot Wheels Jump Through the Burning Ring of Fire
        • Nov. 25 Paper Rockets & Make Up Day 1
        • Nov. 26 Launch Day & Make Up Day 2
        • Dec. 2 Review for Unit 4 Test on Proj. Motion
        • Dec. 3 TEST 2D Motion Unit 4
        • Dec. 4 Early Release Day
      • Unit 5 >
        • Dec. 5 Circular & Harmonic Motion
        • Dec. 6 G on an Egg Lab
        • Dec. 9 Gravitation
        • Dec. 10 Zero G???
        • Dec. 11 Airplanes Airplanes Lab
        • Dec. 12 Circular HW
        • Dec. 13 Pendulum Lab
        • Dec. 16 Hooke's Law Lab-Day 1
        • Dec. 17 Mass on a Spring
        • Dec. 18 Review
        • Dec. 19 TEST
        • Dec. 20 Tops & Spinners
      • Unit 6 >
        • Jan. 2 Egg Design and Building
        • Jan. 3 All-American Egg Drop
        • Jan. 6 no school due to cold 2014 but momentum 2013
        • Jan. 6/7 cold day off 2014/Impulse 2014 Impulse-Momentum 2013
        • Jan. 7 cold day off 2014 but Center of Mass 2013
        • Jan. 8 Impulse 2014 but Center of Mass cont. 2013
        • Jan. 9 Stability 2014 but Conservation of Momentum Lab-Day 1 2013
        • Jan. 10 Center of Mass 2014 but Conservation of Momentum Lab-Day 2 2013
        • Jan. 13 Conservation of Momentum 2014 but Review 2013
        • Jan. 14 Conservation of Momentum 2014 TEST 2013
        • Jan. 15 Scavenger Hunt collection 2014 but OMIT Awards 2013
        • Jan. 16 FINALS (Odd hours)
        • Jan. 17 FINALS (Even hours)
    • Physics 3rd Q >
      • Unit 7 >
        • Jan. 22 Walking on Broken Glass Demo (Pressure, Work)
        • Jan. 23 Energy of Collisions
        • Jan. 24 Laying on a Bed of Nails, PE = mgh
        • Jan. 27 Pile Driver Lab
        • Jan. 28 Joules in a Calorie Lab
        • Jan. 29 How Fast Can You Work? Lab
        • Jan. 30 Power Tube Roll-off
        • Jan. 31 Alka-Bomb Testing
        • Feb. 3 Conservation of Energy
        • Feb. 4 Conservation of Energy
        • Feb. 5 Loop the Loop Lab
        • Feb. 6 Conservation Problems
        • Feb. 7 Dart Gun Lab
        • Feb. 10 Finish home work sheet
        • Feb. 11 Ballistic Pendulum
        • Feb. 12 Review
        • Feb. 13 Test - Energy
        • Feb. 14 Infinities
        • Feb. 14 Mt. Aconcagua
      • Unit 8 >
        • Feb. 18 Magnetism
        • Feb. 19 Magnetism
        • Feb. 20 Electromagnetism
        • Feb. 21 It Can't Work Lab
        • Feb. 24 Electrostatics
        • Feb. 25 Charging/Van de Graff
        • Feb. 26 Static uses
        • Feb. 27 Get a Charge Lab
        • Feb. 28 Coulomb/Millikan Oil Drop
        • Mar. 3 Electrophorus/Wimshirst
        • Mar. 4 Lightning
        • Mar. 5 Leyden Jar
        • Mar. 6 Capacitors
        • Mar. 7 Superconductivity >
          • Capt. Jenkins demo's bottom of Mar. 8
        • Mar. 10 Review
        • Mar. 11 TEST
      • Unit 9 Relativity & Waves >
        • Mar. 12 Relativity
        • Mar. 13 Relativity
        • Mar. 14 Relativity
        • Mar. 17 Waves
        • Mar. 18 Slinnnnnnky Interference
        • Mar. 19 Wave Machine
        • Mar. 20 Hot Sounds
        • Mar. 21 Resonance
    • Physics 4th Q >
      • Unit 9 Continued >
        • Mar. 31 Speed of Sound Lab
        • Apr. 1 Sound of Music
        • Apr. 2 Sound of Music
        • Apr. 3 Doppler Polarization
        • Apr. 4 Laser
        • Apr. 7 Holography
        • Apr. 8 Review
        • Apr. 9 TEST
      • Unit 10 Reflection Unit >
        • Apr. 10 TCOB Awards
        • Apr. 11 Reflection
        • Apr. 14 Draw Your Face Lab
        • continue >
          • Apr. 28 Illusions/Review
          • Apr. 28 Review/Illusions Cont.
          • Apr. 29 TEST
          • April 30 Pre-Great America
          • May 1 Physics Great America
          • May 2 Review PGA
        • Apr. 15 Parallax Blue Skies Scattering
        • Apr. 16 Reflection Lab parts 1 &2
        • Apr. 17 Part 3 of Reflection of Light Lab and Magic Cylinder
        • Apr. 21 Light Bulbs/LUX/LM/Blue Moon
        • Apr. 22 Concave Mirrors
        • Apr. 23 Convex Mirrors
        • Apr. 24 Ripple Tank Lab-Day 1
        • Apr. 25 Ripple Tank Lab-Day 2
      • Unit 11 Refraction Unit >
        • May 5 Refraction Unit Day 1
        • May 6 Refraction Effects - The Eye
        • May 7 Refraction Lab Day 1
        • May 8 Refraction Lab Day 2
        • May 9 Ray Diagrams
        • May 12 2 WAY MIRROR & HMWK
        • May 13 Lens Lab
        • May 14 Total Internal Reflection (TIR)
        • May 15 Rainbows/Mirages
        • May 16 3-D & Refraction Effects
        • May 19 Review
        • May 20 Test
        • May 21 Go Over Test
        • May 22 Senior's Last Day
      • Final Stuff >
        • May 23 Rocket Project Physics
        • May 27 Rocket Project Physics
        • May 28 Rocket Project Physics
        • May 29/30 Rocket Project Physics
        • June 2/3/4 Launch!
      • Videos 2011-2012 >
        • Period 1
        • Period 2
        • Vector Bowling
        • Period 4
        • Period 6
        • Period 7
        • Period 8
        • Pole Vault Practice W=KE=PE=Q
      • Rocket Launches 6/02/14 >
        • period 1
        • period 2
        • period 3
        • period 4
        • period 7
        • period 8
      • Rocket Launches 6/3/13 >
        • Periods 1,4 pictures 5,7,8
      • Rocket Launches 6/01/2012 >
        • Period 1
        • Period 2
        • Period 4
        • Period 6
        • Period 7
        • Period 8
        • Physics memories...
        • Physics 4th Q 2011-2012 >
          • Unit 8: Electrostatics, Magnetism, and Superconductors
          • Unit 9: Waves, sound, polarization, holograms
          • Unit 10 reflection of light and ripple tank
          • Unit 11 Refraction of Light
    • AP PHYSICS B >
      • Post Test options
      • Grading Plan till year end
      • Answers to text book Questions >
        • Chapters 1-8 >
          • Chapter 1
          • Chapter 2
          • Chapter 3
          • Chapter 4
          • Chapter 5
          • Chapter 6
          • Chapter 7
          • Chapter 8
        • Chapters 9-16 >
          • Chapter 9
          • Chapter 10
          • Chapter 11
          • Chapter 12
          • Chapter 13
          • Chapter 14
          • Chapter 15
          • Chapter 16
        • Chapters 17-24 >
          • Chapter 17
          • Chapter 18
          • Chapter 19
          • Chapter 20
          • Chapter 21
          • Chapter 22
          • Chapter 23
          • Chapter 24
        • Chapters 25-31
      • Period 3 videos
      • Calendar
      • Mechanics >
        • Sept 10 Dimensional Analysis
      • Chapter 9 Fluid Dynamics
      • Chap 13 Simple Harmonic Motion, Waves
      • Chap 15 Electric Forces and Electric Fields
      • Chap 16 Electrical Energy and Capacitance
      • Chap 17 Current and Resistance
      • Chapter 18 DC Circuits
      • Chapter 19 Magnetism
      • Chapter 20.1-20.3 Induced Voltages and Inductance
      • Chapter 27 Quantum Physics
    • AP PHYSICS C >
      • College Credit for AP
      • Princeton Exam 1 Free Response
      • Bull's Eye Lab the AP Way
      • Plover Water System Videos
      • 3rd Q >
        • Jan. 29 - Dot Product, Cross Product, Magnetic Flux
        • Jan. 30 - Faraday's Law
        • Jan. 31 - Motor Demos and CH 20 review
        • Feb. 1 - Practice Mech Exam
        • Feb. 4 - Review Practice Mech #1
        • Feb. 5 - Generators, RL Circuits
        • Feb. 6 - Demos with AP-B
        • Feb. 7 - Chapter 20 Hmwk and Practice Exam Work Day
        • Feb. 8 - Practice Exam Problems
        • Feb. 11 - What is AP Looking For?
        • Feb. 12 - Coulomb's Law
        • Feb. 13 - Short Day
        • Feb. 14 - Practice Problem #3 and 15.4-15.6
        • Feb. 15
        • Feb. 18
    • Physics Sharing >
      • writing references
      • Forces on an Incline Plane
      • Resolution of a Force
  • Astronomy
    • 5 MUST SEE VIDEOS
    • Learn Constellations & Stars/Star Trails explained
    • Astronomy Text Condensed
    • Comets & Asteroids >
      • Comets (Halley's Comet, Keiper Belt, Oort Cloud (four short videos)
      • Asteroids (1 short video) Keiper Belt
    • UFO UNIT
    • VENUS TRANSIT VIDEOS >
      • Venus Transit 1st dozen videos taken
      • Venus Transit next 16 videos
      • Two more videos & a picture
      • Mr. Bill Jenkins Transit Day Pictures
      • My SMART PHONE pictures
      • Learning the Sky
    • 3rd quarter 2014 >
      • Jan 22 GNATS 1 FUN MOTIONS of THE SKY
      • Jan 23 GNATS 2 IMPROVED CALENDAR
      • Jan 23 GNATS 3 TIME ZONES
      • Feb 3rd
      • Feb 4th
      • Feb 5th
      • Feb 6th
      • Feb 7th
      • Feb 10th Chap. 3 Copernican Rev
      • Feb 13th Finish Chap 4 Going There
      • Feb 14th TOSA (Top of South America Expedition) Aconcagua
      • Feb 19th Area of a Sphere -
      • March 3rd Chapter 6 The Earth Lecture
      • Teacher Planning
    • 4th quarter 2014
  • Pythagorean Triplets
    • Pythagorean Triplets
    • MATH 111 >
      • The Class Songs
      • Course Info.
      • Homework & my solutions
      • Class Notes & Extra Problems
      • Quizzes & Exams & my solutions
      • Extra Credit & GNATS
      • Solutions to Hmwk
      • Getting Hooked on Math
    • Dr. George Kung
  • Rubics Cube
    • Photo Solution >
      • Vocabulary of Solution
      • Step 1 of 7
      • Step 2 of 7
      • Step 3 of 7
      • Step 4 of 7
      • Step 5 of 7
      • Step 6 of 7
      • Step 7 of 7
    • Abbreviated Solution
    • Original Solution
  • Ancestry
    • My DNA Results Explained
    • My Grandparents ///////////////// 9 Generations >
      • My Paternal Grandfather's Side
      • My Paternal Grandmother's Side
      • My Maternal Grandfather's Side
      • My Maternal Grandmother's Side
    • Ava & Emmett's Grandparents 1st - 9th >
      • 10th Grandparents
    • Ancestry of Grandchildren (actual immigration papers!)
    • Grandchildren to Adam Ancestry on BOTH Ava's mom & dad's sides
    • Ancestry & Inventions
    • Moms Clark Photo Album
    • My Dads Paternal Side >
      • 1 John & Elizabeth Konichek
      • 2 Joseph & Mary Konichek >
        • 3 William J Konichek
        • 3 John Konichek
        • 3 Kate Konichek
        • 3 Fred Konichek
      • 3 Frank & Anna Konichek
      • 4 Edward & Mary Konichek >
        • 5 Mamie Konichek
        • 5 Elsie Konichek
      • 5 Leo & Dorothy Konichek
      • 6 Paul & Judith Konichek >
        • Judy's m, p,, p, maternal side
        • Judy's m, m, paternal
        • Judy's m, m, maternal
        • Judy's maternal paternal, maternal
        • Judy's paternal side
    • My Dads Maternal Side >
      • 1 Tomas & Rosalie Mezera
      • 2 Mathias & Josephine Mezera
      • 3 Frank Mezera & Anna Chvatal
      • 4 Mary Mezera & Edward Konichek
      • 5 Leo & Dorothy Konichek
      • 6 Paul & Judith Koniichek
    • Leo & Dorothy Konichek Genealogy >
      • Clarence & Carolyn Bierman
      • Floyd & Sue Konichek
      • Steve & Donna Metzger
      • Paul & Judy Konichek >
        • Alissa & Fred's Published Articles
        • Drew & Sam >
          • Church Entrance
          • The Vows
          • Reception
      • Greg & Mary Mandigo >
        • Greg and Jamie
    • Family Birthdays >
      • Birthdays by Month
      • Birthdays by Family
      • Birthdays by Age
      • Konichek family by generation
  • Infinities
  • Other
    • Space Foundation Teacher Liaisons >
      • Workshop Presentation 2019 >
        • Lights Off Learning
        • Astronomy Five Must See Videos
        • Mental Multiplying
        • To Infinity & Beyond
        • NIM (a game opening ones first door to learning about bases)
      • The 2015 Space Foundation Teacher Liaison
      • How to Become a Space Foundation Teacher Liaison
      • 31st National Space Symposium
      • What is the Space Foundation?
      • 29th Space Symposium >
        • Pre and Start of Opening Ceremony
        • Opening Ceremony (cont.)
        • Workshops Tuesday
        • Other
    • Christianity/Math/Science >
      • No Volume in Heaven
      • Rational Man cooping with Irrational #'s
      • My Second Sermon Story
      • Variety in Religions & People?
      • Math Proof of Christianity
      • Matter is the exception
      • Jesus Stories of My Life
    • Scouts >
      • Bernoulli's Principle
    • Homecoming >
      • Mr. SPASH BACKWARDS 2nd Half
      • Mr. SPASH 1ST HALF
      • Parade
      • Pep Rally
      • Prom
    • Barbershop
    • Newspaper >
      • Astronomy (40 articles) empty
      • Untitled
      • Math (evolves into math) >
        • All the number systems...
        • The next 13 (empty)
        • The final 13 (empty)
      • Physics (evolves into Physics)
    • Comp Prog >
      • First Half >
        • Arrays
        • Projects
        • Graphics
        • Integer Programs
      • Second Half >
        • Logic Programs
        • Math and Science Programs
        • Statistics and Finance Programs
        • Two Easy Programs
        • $ Programs
        • Cool Bible Facts
  • Mountains
    • HISTORY OF MTS. CLIMBED
    • COLORADO 14er's Summitted
    • Wetterhorn 2015
    • Future Mts. of 2016 >
      • Culebra Peak 7/22/2016
      • Mount Sneffels 7/24/16
      • Grizzly Peak 7/27/2016
    • 50 for Tibet >
      • Itinerary 2013
      • Mt. Pico Videos
      • Andorra Videos
      • Gibraltar Videos
  • Ava & Emmett's Grandparents 1st - 9th
  • Gibraltar Videos
  • Ancestry of Grandchildren (actual immigration papers!)
  • Grandchildren to Adam Ancestry on BOTH Ava's mom & dad's sides

October 15 (Monday) Inertia Problem Solving

If you missed today:  Einstein Board
1.  Reminders:  Push That Cart Lab Due Today by end of day
     and Balloons and Bottle Lab due this Friday as is the extra credit GNATS on Multiplying
2.  Lights Off Learning so review where we are at currently in Physics
3.  Start working on the back side problems on the Unit 2 Problem Sheet (leave the last one for Thursday) and we'll give hints for the grocery sack and elevator ones today.
4. Student volunteers doing inertia tricks that Donatello did last week.
5.  Teacher demonstrating more inertia tricks.

Lights Off Learning:
With students heads down on arms and eyes closed in a darkened classroom...Mr. K. will say something like this:

"Relax, take a deep breath and let it out, erase a white board in your mind for me to assist you in drawing a permanent image of the Physics going on currently that will be there when you need it in your future....

The Last Unit was on Motion ....  There are only two motions in the universe .... namely...... accelerated and non-accelerated.   Accelerated means you are changing your speed (speeding up or slowing down ... or changing direction we'll get to later in the year) so non-acceleration means you are NOT changing your speed (stopped or going the same speed [like 30 MPH or 36,000 MPH].  In the last unit we noticed that to study motion you need to use vocabulary like speed, and acceleration where your average speed is simply the total distance you traveled divided the time it took you to travel it.  And your acceleration is simply your final speed minus your initial speed (your change in speed) divided by the time it took you to change your speed.  In uniform acceleration you can also get your average velocity by simply averaging like in math...adding your initial vel. and final vel. and dividing by two.  Using the top three formulas one can derive two more (one with time and one without time needed to make the fab five formulas)  Also in the first unit we noticed that by noticing the slope of a line tangent at a point in a distance/time graph aided you in seeing the instantaneous velocity and the slope in a velocity/time graph the instantaneous acceleration.

Now in Unit 2 on Acceleration ... Newtons first two laws of motion simply say ...
An object at rest will have a mind of its own (like Garfield) and wish to remain at rest...
   ... and an object in motion (like the hyperbolic velocity Voyager I spacecraft that just left our solar system) will have a mind of its own and wish to stay in motion IN A STRAIGHT LINE unless acted upon by an external net force ....
NEWTON'S 1st LAW is referred to the LAW OF INERTIA because you'll notice from the 2nd law that the more MASS
............................ side note below you may skip .................
(the heavier the object is on Earth ... remembering that everything is weightless in space so to have more inertia in space weight would NOT be the factor but the objects MASS (meaning how much matter ... atoms [electrons, protons, neutrons] make up the object))
............. continued below ...........................
... the more MASS an object has the more inertia thus the more stubborn to stay at rest or in motion in a straight line.


... Ok, so far so good, but now what IF an external net force does act upon this body??? NEWTON'S 2nd LAW

... IF an external net force acts upon this body....the body will accelerate (change its speed or direction) in such a way that this acceleration will be directly related to this net force (more thrust or push or pull ... more acceleration or change in speed) and inversely related to the mass of the body (more massive ... the less acceleration meaning if more massive it will not change its speed or direction as quickly).

... This is why we did the Factors That Affect Acceleration Lab where we took the friction away by using a frictionless cart and noticed the more washers pulling the frictionless cart the more the cart accelerated BUT if we pulled the frictionless cart with the same 10 washers BUT added mass to the cart ... the more mass the cart had, the less the cart accelerated ....

.... Then we did the PUSH THAT TRUCK lab and timed the truck coasting after we stopped pushing (accelerating) the truck to take friction between the tires and the road into account.  So to arrive at the net force we had to add three forces together....namely..... the force to accelerate the inertia of the truck (with and without passengers), the force to accelerate our bodies inertia (the mass of our row pushing the truck), and the force to overcome the constant friction of the tires on the road resisting our efforts to push that truck. ....  This week you'll investigate the properties of friction (the force resisting motion of two objects in contact both for the better and the worse...like marriage).

In the next Unit 3 we will get real involved with the hard to realize fact that Forces Come in Pairs.

Thus to end this "lights off learning"  ... we rethought about Motion in the last unit (fab five, distance/time and velocity/time graphs and how to read them) ... the current unit on Newtons 1st Law of Inertia and 2nd Law of F = ma last week and friction this week .... and look forward to the fact that Forces come in Pairs in the Next Unit on Action ...ReAction.

Now keep your eyes shut as I turn on the lights .... OK, open your eyes slowly and wake up your neighbor gently if they fell asleep...

Get out your Problem Sheet for Unit 2 and notice the problem about accelerating a grocery sack as you lift it.  I think about this problem every time I lift a heavy paper sack of groceries.  I know that if I pick the sack up too quickly ... the handles will break off or the bottom will break out, but if I pick the sack up real slowly the handles and/or the bottom of the paper sack may hold the groceries.  So notice that the problem has two parts... if you pick the sack up extra slow the sack still has take the force of the actual weight of the groceries in the sack; but if you accelerate the sack then you have an additional force added to the weight of the contents to deal with [this acceleration of the sack (F = ma)] so the NET FORCE is the sum of the above two forces.

Also note the elevator problem on the back of the Unit 2 Problem Sheet.  I actually took a weight scale in the SPASH elevator and watched my weight increase the instant the elevator started accelerating me (moving me from the rest state to the non-rest state) up and then as I was moving at a constant speed my weight went back to normal on the scale.  Reversely, when the elevator started taking me back down to 1st floor (negative acceleration, from rest at the top and starting to drop me) the weight scale indicated I weighed less for a brief moment until as I went down at a constant speed the scale read my true weight again.  Think, as you solve this problem, what weight reading would you use in this problem...your true weight, the highest weight the scale read, the lowest weight the scale read, or the difference of the real weight and the other weights????


The below youtube video may help you understand Newton's 1st Law of Inertia better...

Did We Actually attempt the below youtube video inertia demonstration in our class?

The below youtube video helps you see more everyday inertia happenings we demonstrated in class.

How about a few of our videos ... Pulling tablecloth from under plates.  ENJOY! 2012 videos