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Monday, November 18, 2013 H Physics

Warm Up A ball travels 50 meters to the west in 20 seconds. Find the speed of the ball. Find the velocity of the ball. . Monday, November 18, 2013 H Physics. Standards : 1c Newton’s 2 nd Law of Motion Objective SWBAT draw free body diagrams Agenda : Warm Up

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Monday, November 18, 2013 H Physics

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  1. Warm Up A ball travels 50 meters to the west in 20 seconds. Find the speed of the ball. Find the velocity of the ball. Monday, November 18, 2013 H Physics Standards: 1c Newton’s 2nd Law of Motion Objective SWBAT draw free body diagrams Agenda: Warm Up P.2 Review Graphing Worksheet P.2 Work on Problem Solving P.4 Free Body Diagram Inquiry Homework Study Worksheets for Test P.2 P.4 Homework #FH6 P.2 Test Tomorrow: Study the 2 Bootcamp Worksheets

  2. Warm Up Draw a free body diagram of a skydiver in free-fall while s/he is still speeding up. Tuesday, November 19, 2013 H Physics Standards: 1c Newton’s 2nd Law of Motion Objective: SWBAT create free body diagrams. Agenda Warm Up P.2 Take Test P.4 Free Body Diagram Mini-Lecture Force Stations: Elaborate Section Homework #FH6

  3. Wednesday, November 20, 2013 H Physics Standards: 1c Newton’s 2nd Law of Motion Learning Objective: SWBAT create free body diagrams. Agenda: Warm Up P.2 Finish Exam P.2 Begin Force Stations Lab P.4 Finish Force Stations Lab P.4 Practice Free Body Diagrams Homework #FH6 P.4 Finish Force Stations Lab Warm Up p.2 Draw a diagram for the following scenario: A cart rolls across a table with an applied Force of 10N, a frictional force of 5N, no air resistance, and a mass of 2kg. It’s acceleration is unknown. p.4 Draw a free body diagram of the above scenario.

  4. Thursday, November 21, 2013 H Physics Standards: : 1c Newton’s 2nd Law of Motion Learning Objective: SWBAT solve problems using Free Body Diagrams Agenda Warm Up P.2 Force Stations P.4 Collect Force Stations Lab P.4Free Body Diagram Problem Solving Guided Practice P.4Practice #FH7 Homework #FH7 P.4 Quiz Friday – Free Body Diagrams P.2 #FH6 P.2 Warm Up Draw a Free Body Diagram for a car skidding to a stop.

  5. Warm Up Create a free body diagram of a car driving down a hill where friction & air resistance will affect the car’s motion. Friday , November 22, 2013 H Physics Standards: 1c Newton’s 2nd Law Objective; SWBAT will score 80% on the quiz. Agenda: Warm Up P.4 Quiz 6 P#4 Introduce #FH8 Free Body Diagram Problem Solving P.2 Force Stations Lab P.2 Guided Practice Free Body Diagrams Homework P.2 #FH7 P.4 #FH8

  6. Symbols, units and equations Study Guide Equations: Constant Velocity Constant Acceleration Forces The Two equations of Motion The Two equations of Motion for Falling Objects 1. ag=-9.8m/s2 2.

  7. Types of Forces • From your book p. 94 Table 4-2

  8. Modeling the Graphing Process Step One – label each axis with the symbol and the units being represented by the graph. 1st column x-axis, 2nd column y axis Step Two – Create your x and y axis scales. To create a scale(your numbering system on the graph) look at your smallest and largest data points. Then pick a number sequence (ex. 1,2,3,4 or 2,4,6,8) that will allow all of the points to fit on your graph. Step Three – Plot the Points. Step Four – Make a best fine line. It has to be straight and you need to make it go through the center or through the average of your points. See board for more explanation. Step Five – Find the slope of the graph. Step Six (Honors Only) – Find the equation of the graph by substituting your data into the formula y=mx+b

  9. Force Stations For the full 10 pts of credit requires full completion of explore, explain, elaborate, and evaluate sections. Evaluate is Homework worth 10 points. • Objective: Gain an introduction to free-body diagrams (FBDs), and create accurate FBDs of physical systems at stations around room. • Engage • Watch discovery channel video clip on the physics of skydiving (~3 min.): http:/www.youtube.com/watch?v=ur40O6nQHsw . • Explore • Students rotate around force stations in the room and explore each system ~16 min • Identify the Labeled Station • Explore each station: 2 minutes, identify all the forces acting on the object, and draw all the forces on the object. 1. Object at rest on table 2. Cart rolling across table 3. Object hanging by string 4. Object hanging by two strings at an angle to each other 5. Ball rolling down ramp 6. Object stationary on ramp 7. Ball falling through air 8. Coffee filters falling through air • Explain • Mini-lecture on FBDs (Free Body Diagrams) ~5 min • Students revise any force station FBD that is incorrect. • Students finish guided practice problem. • Elaborate • Using magazines provided in class, cut out a picture that shows an interesting physical scenario. Then students create FBD for one or multiple objects in the cutout picture. • Evaluate • “Free-Body Exercises: Linear Motion” #F6

  10. ` ` ` ` HW: #FH6 After you create each free body diagram, use your free body diagram to make an Fnet=ma equation in the x direction and in the y direction like we did during the Explain portion of the lesson. FN FAP FF Ex FAR Fg Fnetx=Fap-Ff-FAR=macar-x-direction Fnety=FN-Fg=macary-direction

  11. Free Body Diagrams ` ` ` ` What are they? – These are diagrams similar to the one’s we are used to drawing, but with one major exception. You only put Forces on them. FN FAP FF Why do we make them? They help us solve problems involving multiple forces. Looking at the diagram to the right. Fnetx=Fap-Ff-FAR Fnety=FN-Fg FAR Fg Question: If the car has a 2000 kg mass, its applied force is 10,000 N, friction is 1500 N, and Air Resistance is 1000 N, find the car’s acceleration and the *Normal Force acting on the car? When do we make them? Remember Fnet=ma? You create a free body diagram to help you find the Fnetportion of this equation. Fnetx=Fap-Ff-FAR=macar-x-direction Fnety=FN-Fg=macary-direction

  12. Free Body Diagrams #FH7 • For each problem: • Draw a Free Body Diagram of the problem. • Make an equation for Net Force in the x (horizontal) and y (vertical) directions. • Then plug in the numbers and Calculate the net force in the x direction and then the y direction. • Find ax and ay • A man pushes a 5kg box with 15 N force to the right while it encounters a 10 N friction force. • An 1kg egg is free-falling from a nest in a tree. Neglect air resistance. • A 2kg flying squirrel is gliding (no flapping wings) from a tree to the ground constant velocity. • A rightward force of 10 N is applied to a 1kg book in order to move it across a desk. Consider a frictional force of 4 N. • A 50kg gymnast is suspended motionless from the ceiling by a bar and two vertical ropes, each with a 25 N force.

  13. Problem Solving using FBD’s #F8 • If a car’s engine accelerates the car using 50,000 N of Force. Friction is resisting the motion with 12,000 N. Find the acceleration of the 2000kg car? • If a 60kg skydiver is freefalling towards the ground, and the air resistance half way to the ground is 500 N. What is the net force on the skydiver? • From Problem 2, what is the acceleration of the skydiver? • If a 70 kg skydiver is freefalling at terminal velocity, what is the air resistance that the free faller is experiencing. • If a 1200 kg car’s engine applies 50,000 N to accelerate the car and it achieves a 2.5m/s2 acceleration, how much friction is acting on the car? (Assume air resistance is negligible.) • If a 20 kg slab of wood is being accelerated on ice at 1.25 m/s2 and friction is small at 5 N. What is the applied force on the slab of wood?

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