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• Centripetal Force - Animations and some good information!
• Definition of Centripetal Force - "A center-seeking net force that is required in order to keep moving objects in a circular path. If the requirement is not met, then objects move into larger curved paths, or go off on a tangent as they follow Newton's First Law." (inertia)
• "Centrifugal" Force: The False Force - Another excellent animation that clearly shows what is happening, and more information.
• Definition of Centrifugal Force - "A non existent force which is actually the absence of centripetal force."
Find these and more at Debbie's Educator's Resources. (Thanks, Debbie!)
(1) p. 261, The Four Fundamental Forces of Creation
Gravity "Rate of acceleration of a falling object is roughly 10m/sec²."
We learned that it is 9.8m/sec², but remember, this video says "roughly."
(3) p. 265b-269, Force and Circular Motion
Centripetal Force, Steve Spangler
Cool and fun! 4 glasses on a tray, spinning around!!!
Centripetal Force
Very similar to the experiment we do in Apologia
(4) p. 269b-273, The Gravitational Force at Work in Our Solar System ► Neat visual of the distances between planets. Sizes are not to scale. The Relative Size of the Planets and the Sun
Orbits of the planets and comets.
You can see that Mercury revolves faster around the sun.
Look on p. 271 for the approximate time for each planet.
Meteorite Crash in Canada Filmed by Police Cam, Nov. 2008
(5) p. 274-276, Comets
A Comet's Nucleus, and how the Comet's Tail reacts when orbiting the sun
Planets and the Kuiper Belt
(6) p. 277-281, What Causes the Gravitational Force? Albert Einstein's General Theory of Relativity
I don't understand this one at all, but it is a theory, (as is the theory of gravity). =)
Excellent graphics.
Graviton Theory
(7) p. 281c-284, A Brief History of Our View of the Solar System
Ptolemaic vs. Copernican Theories
Ptolemy's theory (geocentric - earth is in the center) for the first half of the video,
then Copernicus' theory (heliocentric - sun is in the center).
100 Greatest Discoveries - Astronomy
This is the first 23 minutes of the video to go along with Debbie'sVideo Viewing Guide.
You can watch the entire video here.
Interactive Study Links
• Create an account and make your own flashcards at Quizlet.com!
Other Study Links
• Friction Lesson - lots of information here. Good for educators to read through and get a better understanding and a few ideas. =)
• Comparing Friction Mini-Lab - Page 3 of this pdf is pretty identical to one of the experiments in our book. (It is the 6th page of the document.)
• Newton's Laws with Learning Cycles - great experiments!
Find these and more at Debbie's Educator's Resources. (Thanks, Debbie!)
(1) p. 233-241a, Isaac Newton; Newton's First Law of Motion
Newton's 1st Law of Motion - The Law of Inertia
" An object in motion or at rest will tend to stay in motion or at rest until it is acted upon by an outside force." Inertia - start video at 1:20
Newton's Law of Inertia (seatbelt, headrest)
(2) p. 244-244, Friction
Newton's 1st Law of Motion - Outside forces can be friction and gravity as well as other obvious forces. From this video: 0:00 - 1:50
(3a) p. 244b-250, Newton's Second Law of Motion
Newton's 2nd Law of Motion - the Law of Acceleration
"When an object is acted on by an outside force, the strength of that force is equal to the mass of the object times the resulting acceleration."F=ma Mass
Weight vs. Mass
Newtons' 2nd Law of Motion - F=ma
From this video: 1:50 - 2:48
Dr. Skateboard - Newton's 2nd Law, F=ma, and a=F/m
Overcoming Static Friction... to Kinetic Friction
From this video, 0:00 - 0:30
(3b) Doing the math: Newton's Second Law of Motion: F = ma
The above video shows how to do the math to get the net force of Newtons.
In this example, there was no friction except for air, and it is so small that it isn't taken into account when finding the amount of force the javelin thrower exerted.
Since there was no friction, no other calculations were needed.
In doing the problems in your textbook, you learn about static friction and kinetic friction, and you learn to include those in your calculations.
Watch this video to understand what exactly is net force.
If you are pushing or pulling on an object, you are exerting force.
If you have friction caused by the object against a surface (like the floor), the applied force minus the frictional force will result in a net force.
If more than one person is pushing or pulling, you add those together for the total applied force.
If there is kinetic frictional force while the object is sliding, and maybe there is additional frictional force if the object is a human resisting you, or a pet dog resisting, you will add those to account for total frictional force.
Total Applied Force - Total Frictional Force = Net Force.
When you work the math as in the video above, you get the net force.
In your textbook, you usually need to do a second step to find either applied force or kinetic frictional force.
I have my kids in my class to, as they are reading the problem, circle any directions (east, south, downwards, etc.), and to circle what the problem is asking for (force a person is exerting or kinetic frictional force).
We then work the F = ma formula to find the net force.
Then we need to either find the applied force or the frictional force.
I have them write this on their paper: _____ _____ _____
ap - ff = nf
They fill in net force with the number of Newtons they found in working out F = ma.
Next they fill in either the total applied force or the total frictional force that is given in the problem.
Then they are able to find out the answer that the problem is asking for.
Acceleration and Force is always in the same direction, and friction is always the opposite of motion.
This makes it easy to figure out which direction to include in their answer.
Example (and I am sure these are not sensible numbers, lol)
A man takes his iguana (mass = 51 kg) out for a walk. The iguana is resisting the man with a force of 88 Newtons. In addition, the static frictional force between the iguana and the ground is 76 Newtons, while the kinetic frictional force is 28 Newtons. The man is determined to get the iguana moving so he pulls on the leash. If the man drags the iguana with an acceleration of 2.8 meters/second² to the south, with what force is the man pulling? __________________________________________________
First you work the formula, F = ma just like in the above video. You will get 142.8 Newtons.
This is the net force. If you were to able to move the iguana and still have this much net force even while he is resisting, adding in the kinetic frictional force of him sliding along the ground, you must be actually exerting much more than 142.8 in order to net 142.8 Newtons.
Fill in the blanks: _____ _____ _____
ap - ff = nf
1. Net force: 142.8 Newtons
2. Frictional force: 88 + 28 = 116 Newtons (total frictional force) The number 88 came from the resistance from the iguana, and the number 28 came from the kinetic frictional force. Since the iguana is moving, we use the kinetic frictional force in our calculations instead of the static frictional force.
3. The problem asks, "with what force is the man pulling?" So we see that we need to add 142.8 Newtons and 116 Newtons to get the applied force of 258.8 Newtons.
4. Since the man is pulling to the south, the answer is "258.8 Newtons south."
If you were looking for kinetic frictional force, you answer would say north because friction always opposes motion.
If you come across problems that say ignoring friction, or if something or someone is moving/sliding with no one pushing or pulling, etc. then you will only need to work the F = ma formula. Why?
Because if you have a net force of 32, and either the friction equals 0 or the absent applied force equals 0, the second part of your problem will look something like this: 32 - 0 = 32
(4) p. 250b-254, Newton's Third Law of Motion
Newton's 3rd Law of Motion - the Law of Interaction
"For every action, there is an equal and opposite reaction."
Newton's 3rd Law of Motion - Science Theater 09
Baking Soda & Vinegar Rocket - Newton's 3rd Law
Newton's 3rd Law of Motion
From this video: 2:50 - end
(4) p. 214-220, Acceleration: The Change in Velocity
What is acceleration?
Finding the rate of acceleration:
Acceleration = final velocity - initial velocity
time
Your answer will have something like feet/second² or miles/hour² andwill need to include a direction. Acceleration always is in a direction.
►Note that Example 9.3 and the 1st example in Example 9.4 are of objects that are falling.
The 2nd example in 9.4 is not. (It is of an object that is slowing down.) Nor is the example in 9.5.
These are all in the same section in your textbook, so just be aware that the same formula (for acceleration) will give varied answers for objects that are not falling, and the same answer every time for objects that are falling.
See the statement below. ↓
"The acceleration due to gravity for any object is 9.8 meters/second² in metric units and 32 feet/second² in English units." -Apologia Physical Science, 1st edition, p. 223
(Lol, that must have been one strong little girl!)
So... what is this per second, per second thing? 32 feet sec
sec ←This is read as "32 feet per second, per second."
It is usually then written as 32 feet/sec². But what does it mean???
It means that each second an object is falling, it increases speed by an additional 32 feet per second.
Like this: 32, 64, 96, 128, 160... etc.
But this is only UNTIL the downward pull of gravity and the upward push of air resistance is equal.
Then the object will begin to fall at a consistent speed.
This is like Example 9.5
I like how he converts more than one type of unit, but uses fewer steps than in our book.
See Example 9.4B
The next-to-last sentence on p. 217 of the first edition of Apologia Physical Science says, "If it is slowing down, its acceleration is in the opposite direction as its velocity."
If you do the math, you will get a negative answer.
So if you are driving east and slowing down, your acceleration would be written as west.
If you were driving north and slowing down, and calculated your velocity to be -15 m/s², you would write it as 15 m/s² south. (no negative and the direction is changed)
►Note: Acceleration is a change in velocity. If you are going at a constant velocity (not changing speed), there is no acceleration. You would say your acceleration is zero.
Abbreviations of units
0:00-3:35 from this video. Also see the awesome Triangle Trick from 9:20-10:45! =)
speed = distance/time.
distance = speed x time
time = distance/speed
(5) p. 220-226, The Acceleration Due to Gravity
Low Gravity.
Objects fall at the same rate in the absence of air resistance.
Physics of Skydiving
You learned about the acceleration of objects as they fall.
Falling objects will accelerate UNTIL the downward pull of gravity and the upward push of air resistance is equal, as when a skydiver falls (as long as he holds his body position the same). Then he will begin to fall at a consistent speed.
Gravity on Falling Objects
The pull of gravity is stronger on a heavier object, true, but inertia equals that out. (Inertia means that objects stay where they are unless acted on by an outside force.) So heavier objects will not fall faster than lighter objects.
I have been unable to find a video for the formula for finding distance for an object in free fall.
You'll just have to read the directions in the textbook and follow the formula carefully.
distance = ½ • acceleration • (time)²
Don't forget to square the time unit.
And use the correct acceleration formula, whether feet or meters.
"The acceleration due to gravity for any object is 9.8 meters/second² in metric units and 32 feet/second² in English units." -Apologia Physical Science, 1st edition, p. 223
Gregor Mendel first experimented with garden peas, which is a self-pollinating plant. (The stigma of the flower receives pollen from its own flower.)
"In order to cross-pollinate these plants, Mendel removed the anthers (with pollen). Then, he transferred the pollen from another plant to the stigma of the first plant. He always kept very careful records on these plants.
Mendel noticed that when he allowed pure tall plants to self-pollinate, they always produced pure tall plants. He also noted that dwarf plants which were allowed to self-pollinate produced only dwarf plants. Whenever he crossed a tall plant with a dwarf plant, the first generation was always tall. He said that tallness was a dominant trait and that dwarfness was a recessive trait." (SOS)
Even though a crossed plant produced a tall plant and looked just like a pure tall plant, it actually was a hybrid. Two hybrid tall plants will not produce tall plants 100% of the time. "Genetic Symbols. Inherited traits are controlled by genes. Scientists use letters to represent the genes. Because genes occur in pairs, two letters represent the genes inherited from each parent. A capital letter is used to represent the dominant gene. A small letter is used to represent the recessive gene.
The first letter of the name of a trait is generally used. Mendel's tall peas could be represented by capital T for tall. The dwarf or recessive gene would be little t. Since genes occur in pairs, tall peas could be TT or Tt. TT is purebred for the tall characteristic. Tt is a hybrid for the tall characteristic. Tall plants with TT genes would look exactly like those with Tt, but the recessive gene (t) is hidden. For the plants to be dwarf, both genes must be recessive (tt)." (SOS)
Quotes are from Switched on Schoolhouse, 6th grade lesson "Inheritance."
1) p. 183, Thunderstorm animation - He goes through it a little fast, but very good.
Watch twice.
2) p. 185, Dew Point and Relative Humidity
"...whenever you see clouds, you know the temperature inside of them and dew point are equal."
3) p. 185, Weather Barometer - high and low pressure
The higher the pressure and humidity, the higher the dew point.
4) p. 186, How to Predict the Weather - from a veteran fisherman and sailor, Jeff Spira. See more videos, some about building boats, at SpiraInternational.com
5) p. 186, Predicting Weather - NASA
6) p. 188, Science Explains Lightning - how the negative charge builds
8) p. 188 - What is lightning? - stepped leaders, return stroke.
Good, but doesn't show the negative and positive charges that are both in the cloud and on land. See previous video.
9) p. 188, How Lightning Works - Unable to chop at TubeChop, but content relative to Module 8 is from 1:12-3:40.
10) p. 192, Hurricane Ike Forecast
with Joe Bastardi (Bu-STAR-dee)
He talks about where the hurricane may hit. Around 2:05 minutes, you will see three arrows pointing toward the coast of Texas. He mentions Corpus Cristi (about where the bottom yellow arrow is) and Brownsville (the very tip of Texas), and that there were fewer people in an area between there. Hurricane Ike actually ended up hitting at the top green arrow, in Galveston, Tx as you can see in the next video via satellite.
11) p. 192, Hurricane Ike via Satellite, hits Galveston, Texas. Slow time-lapse video of 4 days. I recommend hitting play, letting it download while you do something else for a few minutes (watch a video!), then slowly dragging the button across. You will see that Joe was right about it slowing down. In the warmer waters the hurricane did gain back strength that was lost down to a Category 1 after hitting Cuba. According to Wikipedia, Hurricane Ike hit land "as a strong Category 2 hurricane, with Category 5 equivalent storm surge."
11) p. 195, Hurricanes and Meteorologists - from NASA
Full Video of the above, plus 2 more:
Ahead Above the Clouds, Part 1, Part 2, Part 3
12) p. 195, Hurricane Hunters - NASA. At 2:40, note the "eye wall" that is mentioned on p. 194 of the text.
My class had to draw and label the graph as it appears around 3:40.
