***Period 2, there's going to be an earthquake drill. Be ready to go under your tables and hold on. You'll miss some class today, and will need to make that up on your own time. ***
#Goals: SWBAT...
1. Describe the relationship between inertia and mass
2. Match force names to their abbreviations and to their definitions
3. Define force and the unit of force
Warm-Up (5min)
Copy and fill in (or choose) the correct answers for the following:
1. Inertia: the resistance an object has to ______________
2. The more inertia that an object has, the more _____ it has.
3. A more massive object has a (greater/lesser) tendency to resist changes in its state of motion.
4. What is the meaning of "net" in relation to forces?
5. A net external force equal to zero means the forces are (balanced/unbalanced)
6. The presence of a net external force means that the object will be (accelerating/at rest)
7. When people from other countries say they weigh 70kg, what do they really mean?
8. If Fg=mg, what is their weight?
CLASSWORK
1. #039A: What is a force?
Force: Sometimes defined as a push or a pull on an object. Better Definition: A force is the ability to cause a change in state of motion of an object.
Unit: Force is a quantity that is measured using the standard metric unit known as the Newton. A Newton is abbreviated by an "N." To say "10.0 N" means 10.0 Newton of force. One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. Thus, the following unit equivalency can be stated:
1 Newton = 1 kg • m/s2
Is force a vector?
2. #039B: Force Types and their Classifications
What are the classifications of force?
Take 2 minutes to review Mr. P´s notes, here ---> LINK
Make a four column chart (see example below)
Using your knowledge, and the definitions for forces here LINK, match the symbols/names of the forces with their definitions, then define each for as a ¨contact force¨ or "non-contact/action-at-a-distance/field¨ force.
Definitions:
1. The force exerted by a compressed or stretched spring upon any object that is attached to it.
2. A force that is applied to an object by a person or another object.
3. The force exerted by a surface as an object moves across it or makes an effort to move across it.
4. A special type of frictional force that acts upon objects as they travel through the vacuum you can breathe. This force is often observed to oppose the motion of an object.
5. The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself.(aka weight)
6. the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends
7. The support force exerted upon an object that is in contact with another stable object
Symbols/Names:
Applied Force Fa
Gravitational Force Fg
Normal Force FN
Force of Friction Ff
Air Resistance Fair
Tension Force Ftension
Spring Force Fspring
3. #039C: Force Scenarios
Which forces are being applied here? What are the two objects exerting/feeling the force?
A. A dog pulls on a leash.
B. A hammer hits a nail.
C. You fall out of a tree toward the Earth
D. A car slides to a stop.
4. #039D: Are Mass and Weight the Same?
What do you think?
Mass is how much ______ is in an object. In science, we call that stuff _____
Weight is the _____ of _______ upon that stuff.
Which is a force, weight or mass?
5. #039E: Practice Questions
LINK Answer 1, 2, and 3 (complete outside of class if necessary - I'm here at lunch/nutrition for help)
Learning at Home (HW)
1. Complete any incomplete classwork\
2. Notebook check for this week (day 36-39) on Friday 10/18
3. Lab 3 due Saturday 11:59 pm. Last day to test is this Friday
4. Kinematics Exam Friday. Study Guide: LINK
#Goals: SWBAT...
1. choose the appropriate UAM equation
2. use algebra to solve for the unknown
3. solve kinematics problems independently
4. consider two objects, and describe which has greater inertia
5. clearly express their lab procedure
Warm-Up (5min)
If your given information and unknown include the following, which UAM equation should you choose?
After choosing an equation, rearrange it to solve for the unknown.
1. given: vi, a, Δt unknown: Δx
2. given: vi, vf, Δx unknown: Δt
CLASSWORK
1. #039A: "Practice Doesn't Make Perfect, but Practice Does Make You Better" - Tiya M. (8min)
Set-up and solve a two dimensional free-fall problem
"A toy car runs off the edge of a table that is 1.225m high. The car lands 0.400m from the base of the table."
a. How long did it take the car to fall?
b. How fast was the car going on the table?
2. #039B: HW Review (link to the notes you should have: NOTES) (3min)
3. #039C: Lab Write-Up, Pt. 1
Title your Lab: Lab #2: Projectile Motion: Ball in a Cup
For today, you need the following sections: title, group member names, purpose (it's HERE in the pre-lab) (there was no hypothesis), materials, procedure (for a procedure example, here's the link to Lab #1, LINK)
Tomorrow we'll discuss your conclusion
Lab write-up will be due Wednesday of next week
While you collected data as a group, and can consult with group-mates to discuss errors and calculations, your lab write-up is your own work.
Grading Rubric LINK
Lab Template: LINK
At Home Learning (HW)
Two short videos
1. #039D:
INERTIA
Take Notes: LINK 1
Watch the video, and answer the EdPuzzle Questions: LINK 2
FORCE
Take Notes: LINK 1
Watch the video, and answer the EdPuzzle Questions: LINK 2
2. #039E: Exam #1 Revisions
This class is all about mastery. I want you to keep trying until you understand each concept, and until you can solve each problem. To that end....you may make corrections to problems on the test. Here are the guidelines for that:
You may redo one problem from each of the four sections of the test, for a total of (up to) four problems redone.
The four sections are: Conversions (1-4); SigFigs (5-11); Graphing (12-17); Acceleration (19-22)
You must write neatly. If I can't read it, I can't grade it
For each problem, you must show work or explain your answer. If the problem includes math, you must show your GUESS method steps, use sigfigs, use units, and box your answer.
I'll post the test on the website Thursday after school, as some students still need to make it up, and any redone problems must be turned in by the following Monday.
When you turn in your redone problems, please staple the original Scantron answer document to your redone problems.
Exam link here: LINK
#Goals: SWBAT...
1. Write & understand the equations for Kinetic and Potential Energy
2. Set an appropriate reference (zero) line.
3. Solve KE and PE problems
***Warm up check for Day 30-38 (9 warm-ups total) will be today, Monday 03/05***
Warm-Up (4min): Review KE and PE from this weekend's learning at home videos
1. Write the equation for Potential Energy (PEg)
2. If you're measuring the PEg of a basketball being thrown above the ground, which location of the reference (zero) line makes the most sense?
i. setting the line at the ball's highest possible position?
ii. setting the line at the ball's lowest possible position?
iii. setting the line at the average of the ball's lowest and highest positions?
3. Write the equation for Kinetic Energy (KE).
4. If you double the velocity of an object, the KE value quadruples. If instead, you triple the velocity, what happens to the value of the KE? Hint: think about what the v2 part of the equation means....
5. Is PEg a vector or scalar? What about KE?
CLASSWORK
1. #039A: Potential Energy: Notes
Definition: Potential energy is the stored energy of position possessed by an object.
What does that mean? There is a direct relation between gravitational potential energy and the mass of an object. More massive objects have greater gravitational potential energy. There is also a direct relation between gravitational potential energy and the height of an object. The higher that an object is elevated, the greater the gravitational potential energy.
Equation: PEg = mass • gravity • height
or... PEg = m • g • h
In the above equation, m represents the mass of the object, h represents the height of the object and grepresents the gravitational field strength (9.8 N/kg on Earth) - sometimes referred to as the acceleration of gravity
Check for Understanding: If you double the height of an object, what happens to the PEg?
2. #039B: Kinetic Energy: Notes
Definition: Kinetic energy is the energy of motion
The kinetic energy of an object is directly proportional to the square of its speed.
That means that for a twofold increase in speed, the kinetic energy will increase by a factor of four. For a threefold increase in speed, the kinetic energy will increase by a factor of nine. And for a fourfold increase in speed, the kinetic energy will increase by a factor of __________. The kinetic energy is dependent upon the square of the speed.
Equation: KE = 1/2 • m • v2
where m = mass of object
v = speed of object
You can often trade KE for PE, and vise versa. We'll learn more about that kind of Conservation of _________ tomorrow
3. #039C: PEg and KE Practice Problems
1. A cart is loaded with a brick and pulled at constant speed along an inclined plane to the height of a seat-top. If the mass of the loaded cart is 3.0 kg and the height of the seat top is 0.45 meters, then what is the potential energy of the loaded cart at the height of the seat-top?
2. If a force of 14.7 N is used to drag the loaded cart (from previous question) along the incline for a distance of 0.90 meters, then how much work is done on the loaded cart?
***Note that the work done to lift the loaded cart up the inclined plane at constant speed is equal to the potential energy change of the cart. This is not coincidental! More on Mechanical Energy, and how energies change from one type to another...tomorrow. ***
3. Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s.
4. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy?
5. Missy Diwater, the former platform diver for the Ringling Brother's Circus, had a kinetic energy of 12,000-J just prior to hitting the bucket of water. If Missy's mass is 40-kg, then what is her speed?
6. A 900-kg compact car moving at 60 mi/hr has approximately 320 000 Joules of kinetic energy. Estimate its new kinetic energy if it is moving at 30 mi/hr. (HINT: use the kinetic energy equation as a "guide to thinking.")
7. THE BIG KAHUNA:
A comet with a mass of 7.85 x 1011 kg strikes Earth at a speed of 25.0 km/s. Find the kinetic energy of the comet in joules, and compare the work that is done by Earth in stopping the comet to the 4.2 x 1015 J of energy that was released by the largest nuclear weapon ever built. (post-class notes: I prematurely assigned this problem - should have given it to you in a few days. That said, you can still solve it with this one piece of information. In addition to Work being equal to Fdcos(Θ), Work is also equal to the change in Kinetic Energy (KE). This is called the Work-Energy Theorem, and the equation for it is this: W= ΔKE. Consider that Δ means KEf-KEi, and that you know the final KE of the comet (it's at rest) and you should have no problem solving).
At Home Learning (HW)
1. Complete all problems from #039C
If you got stuck, answers and more help are here at these links:
- PE LINK
- KE LINK
2. #039D: Tuesday we will cover Mechanical Energy: Watch/take notes/complete edPuzzle on the following:
(8:26) Introduction to Conservation of Mechanical Energy with Demonstrations - EDpuzzle