DAY 44
#Goals: SWBAT...
1. Draw correct FBD's, with appropriate vector magnitude and direction.
2. Support classmates with helpful tutoring
3. Use FBD's to find Net Force
4. Describe the relationship between mass, net force, and acceleration
Warm-Up (4min)
Copy or complete the following:
1. Complete the FBD on the board
2. Which requires more force to accelerate? A desk or a chair? Why?
3. If you apply the same force to a bike, and to a train locomotive, which will accelerate faster? Why?
0. 044A: Quiz: FBD's
Answer the following (3min)
1. Ariana Grande drops a Pete Davidson bobblehead straight down from her 17th story apartment. Draw the FBD. Neglect air resistance
2. A truck is moving to the left and slowing down. Neglect air resistance. Draw the FBD showing the forces acting upon the truck.
CLASSWORK
1. 044B: HW Review, AKA You thought your dad went to the store for milk and never came back? Well, he’s back... (5min)
2. 044C: Newton's 2nd Law
Read, then take Notes: (5min)
Write the equation for Newton's 2nd Law
Newton's second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object.
The acceleration of an object depends (directly/inversely) upon the net force acting upon the object, and (directly/inversely) upon the mass of the object.
As the force acting upon an object is increased, the acceleration of the object is (increased/decreased).
As the mass of an object is increased, the acceleration of the object is (increased/decreased).
2. 044D: The Reality of Our First Free Body Diagrams (6min)
Are our FBD's accurate? Yes/No? Why or why not?
Watch, take notes, and answer the two Edpuzzle questions in your notes.
https://edpuzzle.com/media/5808e44e892b65ec3e6b874d
3. 044E: Practice Finding Net Force and Applying Newton's 2nd Law
A. A Net Force Causes Acceleration - Practice Problems
Read EVERYTHING. If you come across material that you haven't already mastered, TAKE NOTES.
Looking at the Description of Motion section (pics of cars and v-t graphs), what is the net force for each scenario? (answers can be positive, negative, or zero). Discuss why the answers are what they are with your neighbor.
Draw the FBD's in your notes. There are 8 in total. Find the missing forces, or Net Force (Fnet). For each FBD, assume the mass of the object is 5kg, and once you've found the all the missing forces, or Fnet, find the acceleration of the object. For problem #2, there are separate x and y accelerations. Get peer help if needed. Fnet answers are in the orange links on The Physics Classroom. Acceleration answers will be posted below in lite grey text - highlight it to reveal the truth!
Link to the reading and practice problems is ---> HERE
ACCELERATION ANSWERS
1a. a = 0m/s2
1b. a = -1m/s2
1c. a = 0m/s2
1d. a = 3m/s2
2a/b. ax = 0m/s2 ay = 0m/s2
2c. ay = 180m/s2
2d/e. ay = 0m/s2 ax = -12m/s2
2f/g/h ay = 0m/s2 ax = 6m/s2.
At Home Learning (HW)
1. Quiz Friday on FBD's. review the following... Day 41-44
2. Complete any unfinished practice problems from this week for HW
3, 044F: Due Friday: Prepare for class by reviewing Newton's 1st and 2nd Laws along with Mr. P's class
Watch the video, and answer the EdPuzzle Questions: EDpuzzle
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--
Jenny Kopach
Science Olympiad
Executive Director
SVP Marketing Communications
National Executive Board Member
Two Trans Am Plaza Drive, Suite 310
Oakbrook Terrace, IL 60181
(630) 792-1251 phone
(630) 792-1287 fax
Facebook: SOAlumniNetwork
Twitter: @SOAlumniNetwork
#Goals: SWBAT...
1. Draw correct FBD's, with appropriate vector magnitude and direction.
2. Support classmates with helpful tutoring
3. Use FBD's to find Net Force
Warm-Up (4min)
Copy and answer the following:
1. What is the equation which represents Newton's 2nd Law of Motion?
2. What mathematical operation does Σ represent?
3. What are the units of a Newton?
4. Draw a free body diagram representing a book, sliding on a horizontal table, with applied force of +10.0N, and friction of -4.5N.
CLASSWORK
1. Tutoring: Modeling and Practice
We're going to continue to help each other. From yesterday, here's our list of best tutoring practices:
Don't give student the answer
let student think on their own
ask guiding questions
guide student to figure out mistakes
be nice, calm, patient, supportive
try to make student solve problem
review the topic (this is a great way to guide students thru finding their mistake)
give a person a fish vs. teach a person to fish
2. #044A: Practice Problems
A book is at rest on a tabletop. Diagram the forces acting on the book.
A gymnast holding onto a bar, is suspended motionless in mid-air. The bar is supported by two ropes that attach to the ceiling. Diagram the forces acting on the combination of gymnast and bar.
An egg is free-falling from a nest in a tree. Neglect air resistance. Diagram the forces acting on the egg as it is falling.
A flying squirrel is gliding straight down (no flapping of the wings) from a tree to the ground at constant velocity. Consider air resistance. Diagram the forces acting on the squirrel.
A rightward force is applied to a book in order to move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.
A rightward force is applied to a book in order to move it across a desk at constant velocity. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.
A college student rests a backpack upon his shoulder. The pack is suspended motionless by one strap from one shoulder. Diagram the vertical forces acting on the backpack.
A skydiver is descending with a constant velocity. Consider air resistance. Diagram the forces acting upon the skydiver.
A force is applied to the right to drag a sled across loosely packed snow with a rightward acceleration. Neglect air resistance. Diagram the forces acting upon the sled.
A football is moving upwards towards its peak after having been booted by the punter. Neglect air resistance. Diagram the forces acting upon the football as it rises upward towards its peak.
A car is coasting to the right and slowing down. Neglect air resistance. Diagram the forces acting upon the car
Need the answers to #044A? There will be a video posted HERE after school ends.
3. #044B: Determining the Net Force
Notes:
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
If either all the vertical forces (up and down) do not cancel each other and/or all horizontal forces do not cancel each other, then an unbalanced force exists.
Review the following. Are the forces balanced?
If the forces are unbalanced, a NET FORCE exists
What is the net force in each of the above?
So what? Well, a net force causes acceleration, and we can use that fact to solve problems.
4. #044C: (save for Friday) A Net Force Causes Acceleration - Practice Problems
Navigate to: http://www.physicsclassroom.com/class/newtlaws/Lesson-2/Determining-the-Net-Force
Scroll halfway down the page to "A Net Force Causes Acceleration "
Looking at the Descriptions of Motion, what is the net force for each scenario? (answers can be positive, negative, or zero)
Try the two Check for Understanding problems on your own for practice. Get peer help if needed.
At Home Learning (HW)
1. Friday we will take a two question FBD quiz. Prepare yourself. Review notes, videos, and practice problems from Day 43 & 44.
2. #044C: Your homework, due Friday, is to prepare for class by watching 8.5 minutes worth of video. You should understand how to solve net force problems after watching the video
Take Notes: Introductory Newton's 2nd Law Example Problem
Watch the video, and answer the EdPuzzle Questions: EDpuzzle
NGSS Standard
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship amongthe net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object sliding down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]
Quiz 6: FBD's
draw object. label forces. use appropriate size force vectors.
A force is applied to the left to drag a cooler across loosely packed sand with a leftward acceleration.
Neglect air resistance. Diagram the forces acting upon the cooler.
A baseball is moving upwards towards its peak after having been hit by the batter. Neglect
air resistance. Diagram the forces acting upon the baseball as it rises upward towards its peak.
#Goals: SWBAT...
1. Categorize forces as internal or external
2. Understand how internal vs. external forces affect the TME
3. Answer medium difficulty energy problems with conservative and non-conservative forces
Warm-Up (5min): Internal vs. External Forces/PE vs. KE/ + - Work
Answers to Warm-up A and C are on the board.... read, draw the image, then solve
As the pendulum bob swings to and fro, its height above the tabletop (and in turn its speed) is constantly changing. As the height decreases, potential energyis lost; and simultaneously the kinetic energy is gained. Yet at all times, the sum of the potential and kinetic energies of the bob remains constant. The total mechanical energy is 6 J. There is no loss or gain of mechanical energy, only a transformation from kinetic energy to potential energy (and vice versa). This is depicted in the diagram below, which you should copy into your warm-up.
As the 2.0-kg pendulum bob in the above diagram swings to and fro, its height and speed change. Use energy equations and the above data to determine the blanks in the above diagram.
ANSWERS:
A: h = 0.306 m (6 J = 2 kg *9.8 m/s/s * h)
B: h = 0.153 m (3 J = 2 kg *9.8 m/s/s * h)
C: v = 1.73 m/s (3 J = 0.5 * 2 kg * v2)
D: h = 0 m (0 J = 2 kg * 9.8 m/s/s*h)
E: v = 2.45 m/s (6 J = 0.5 * 2 kg * v2)
F: h = 0.306 m (6 J = 2 kg * 9.8 m/s/s * h)
CLASSWORK
1. #044A: ROLLER COASTERS and ENERGY
For this activity, you'll work alone, or with one partner
Goal: investigate the energy relationship between KE and PEg for a roller coaster car
LINK to activity.
Absent today: here's the link to the handout: HANDOUT
2. #044B: PRACTICE PROBLEMS
At Home Learning (HW)
1. Recall: There is a relationship between work and mechanical energy change. Whenever work is done upon an object by an external or nonconservative force, there will be a change in the total mechanical energy of the object. If only internal forces are doing work (no work done by external forces), there is no change in total mechanical energy; the total mechanical energy is said to be "conserved." The quantitative relationship between work and the two forms of mechanical energy is expressed by the following equation:
KEi + PEi + Wext = KEf + PEf
2. Problem Solving:
Use your understanding of the work-energy equation to answer the following questions.
Consider the falling and rolling motion of the ball in the following two resistance-free situations. In one situation, the ball falls off the top of the platform to the floor. In the other situation, the ball rolls from the top of the platform along the staircase-like pathway to the floor. For each situation, indicate what types of forces are doing work upon the ball. Indicate whether the energy of the ball is conserved and explain why. Finally, fill in the blanks for the 2-kg ball.
Quiz 6: Version 2
An egg is free-falling from a nest in a tree. Neglect air resistance. Diagram the forces acting on the egg as it is falling.
A rightward force is applied to a book in order to move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.
Quiz 6: Version 3
1. A skydiver is descending with a constant velocity. Consider air resistance. Diagram the forces acting upon the skydiver.
2. A car is coasting to the right and slowing down. Neglect air resistance. Diagram the forces acting upon the car