AP PHYSICS MONDAY STANDARDS: KINEMATICS 1D & 2D: BIG IDEA 3 Agenda: 1.Warm Up 2.Stamp HW 3.Review Quiz 4.Work on Lab. Homework Fap#8 Warm Up a.Based on the diagram below, will the box accelerate? b.If yes, how much will it accelerate c.What is the normal force holding up the block. Standards: 3a3 A force exerted on an object is always due to the interaction of that object with another object I –Independent Resilient Individuals RST Synthesize information from a range of sources into coherent understanding of a process, phenomenon, or concept,… Learning Goal: SWBAT find the coefficient of friction of the table & use that to predict the sliding angle of a mass on a ramp. 50kg 20° 40 N μ s =.3, μ k =0.25

AP PHYSICS WEDNESDAY STANDARDS: 3A3 A FORCE EXERTED ON AN OBJECT IS ALWAYS DUE TO THE INTERACTION OF THAT OBJECT WITH ANOTHER OBJECT I –INDEPENDENT RESILIENT INDIVIDUALS RST SYNTHESIZE INFORMATION FROM A RANGE OF SOURCES INTO COHERENT UNDERSTANDING OF A PROCESS, PHENOMENON, OR CONCEPT,… Agenda: 1.Warm Up 2.Review HW 3.Grade Quizzes 4.Finalize Friction Experiment 5.Newton’s 3 rd Law Activity Learning Goal: SWBAT use Newton’s 3 rd Law of Motion to understand the physics of complex force interactions. Homework Fap#9 Warm Up You want to find the coefficient of static & kinetic friction between a tire and the asphalt road. Explain what you would do experimentally to find μ s and μ k. 60°

AP PHYSICS THURSDAY I- INDEPENDENT, RESILIENT IND. STANDARDS: 3A3 A FORCE EXERTED ON AN OBJECT IS ALWAYS DUE TO THE INTERACTION OF THAT OBJECT WITH ANOTHER OBJECT RST SYNTHESIZE INFORMATION FROM A RANGE OF SOURCES INTO COHERENT UNDERSTANDING OF A PROCESS, PHENOMENON, OR CONCEPT,… WHST : RESEARCH TO AID IN PROBLEM SOLVING Agenda: 1.Warm Up 2.Newton’s 3 rd Law Activity 3.Pulleys Homework Fap#10 Warm Up Identify and label all of the force pairs between a horse, cart, and the ground. Learning Goal: SWBAT identify force pairs in Newton’s 3 rd Law.

Agenda 1.Warm Up 2.Stamp HW 3.Review HW#6,#10 4.Acceleration of a cart & Pulley Homework FAP #11 Warm Up Identify the force pairs and draw a free body diagram for each mass in the system. Learning Goal: SWBAT collect data from a pulley system AP Physics Friday Standards: 3a3 A force exerted on an object is always due to the interaction of that object with another object RST Meaning of symbols, key terms, technical jargon Problem Solvers m M

NEWTON’S 3 RD LAW ACTIVITY 17 1.Newton’s 3 rd Law Means what? - Research in Book and online, write down a definition in your own words. 2.What does that definition mean? Create 2 scenarios or situations where forces are acting. Draw each scenario and label their action/reaction pairs. 1.Example A box on a table. 3.Find all of the action/reaction pairs at each station. W N a.Mass hanging from strings. b.Ball accelerating down a ramp. c.Car decelerating due to friction d.Pith Ball Suspended in air between ruler and Van de Graff e.plastic cap floating on water

NEWTON’S 3 RD LAW PULLY’S 18 There are two main types of pulley setups you will need to be familiar with for the AP Test. 1. Mass & Pulley 2. Atwoods Machine m m M M m M Directions: Build each pulley system. 1.Set up 10g mass and a blue cart a.Calculate the acceleration of the cart. (Hint use 2 FBD’s & create expressions for each) b.Collect distance & time measurements to find the acceleration of the block & mass. c.Find % error. 2.Set up a 40 g & 50 g mass on each side of Atwood’s machine. a.Calculate the acceleration of the cart. b.Measure the change in height over time in order to find the acceleration of the masses. c.Find % error.

TYPES OF FORCES ForceSymbolDefinitionDirection Frictionf or F f Resistive Force. Comes from rubbing against or sliding across surfaces. Parallel to the surface and opposite the direction of sliding NormalN or F N The force exerted on an object by the ground, a table, a platform, or any surface. Perpendicular to and away from the surface. SpringF sp Restoring Force. The push or pull a spring exerts on an object. Opposite the displacements of the object at the end of the spring. TensionT or F T The pull exerted by a string, rope, or cable when attached to something. Away from the object and parallel to the string, rope, or cable at the pont of attachment. ThrustF thrust A general term for the forces that move objects such as rockets, planes, cars and people. In the same direction as the acceleration of the object. WeightW or F g Attractive Force of two objects due to gravity. Usually Earth and and object Straight down towards the center of the earth. Air Resistance/DragF AR Resistive Force, comes from air/wind hitting moving objects Opposite of Motion ElectricFEFE Force between atoms with electric charge (protons & electrons) Like charges repel + Opposite charges attract - MagneticFBFB Force between magnetic poles & force created when electric current is in flux. Same Pole repels Opposite Pole Attracts Applied ForceF AP A Force applied by a person, thing, or individual that does not fall into any of the above categories any

FAP #6 NET FORCE PROBLEMS 1.A rope of negligible mass supports a block that weighs 30 N, as shown to the right. The breaking strength of the rope is 50 N. The largest acceleration that can be given to the block by pulling up on it with the rope without breaking the rope is most nearly what? 2.The cart of mass 10 kg shown below moves without frictional loss on a level table. A 10 N force pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60° above the horizontal pulls on the cart to the left. What is the magnitude of the horizontal acceleration of the cart? 3.A 100 N weight is suspended by 2 chords as shown above. The Tension on the slanted chord is? 4.When an object of weight W is suspended from the center of a massless string the tension at any point in the string is? #4 #3 #2 #1

FAP#4 FRICTION ON AN INCLINED PLANE A block of mass 5 kilograms lies on an inclined plane, as shown above. The horizontal and vertical supports for the plane have lengths of 4 meters and 3 meters, respectively. The coefficient of friction between the plane and the block is 0.3. The magnitude of the force F necessary to pull the block up the plane with constant speed is most nearly.

FAP #5 An empty sled of mass 25 kg slides down a muddy hill with a constant speed of 2.4 m/s. The slope of the hill is inclined at an angle of 15° with the horizontal as shown in the figure above. a. Calculate the time it takes the sled to go 21 m down the slope. b. On the dot below that represents the sled, draw/label a free-body diagram for the sled as it slides down the slope c Calculate the coefficient of friction between the sled and the muddy surface of the slope. d. The sled reaches the bottom of the slope and continues on the horizontal ground. Assume the same coefficient of friction. i. In terms of velocity and acceleration, describe the motion of the sled as it travels on the horizontal ground. ii. On the axes below, sketch a graph of speed v versus time t for the sled. Include both the sled's travel down the slope and across the horizontal ground. Clearly indicate with the symbol t the time at which the sled leaves the slope.

UNDERSTANDING HOW THE FORCE OF FRICTION WORKS #16 a.Find the coefficient of friction down a ramp (using symbols only) μ s =? b.Find the coefficient of kinetic & static friction between a horizontal ramp and a cylinder. (Do this by dragging the cylinder from rest with a Forcemeter & dragging the cylinder while moving with a Forcemeter. Demo will be shown in class.) c.Next we want to prove that our equation for letter a is actually physically true. i.We found μ s experimentally in part b, so plug your values for μ sn into your equation from part a. Solve for θ’s. ii. Now we can find the angle where your masses should begin to slide. iii. Now we can measure the angle that the masses will actually begin to slide. iv. Calculate % difference between the measured and calculated angles.

16 CONTINUED c.Next we want to prove that our equation for letter a is actually physically true. i.We found μ s experimentally in part b, so plug your values for μ sn into your equation from part a. Solve for θ’s. ii. Now we can find the angle where your masses should begin to slide. iii. Now we can measure the angle that the masses will actually begin to slide. iv. Calculate % difference between the measured and calculated angles. % uncertainty = measured – actual actual

FAP#10 m M m m M M 1.Identify the equal and opposite force for each of the following situations. 2.Draw Free Body Diagrams of each. Pulleys require 2 free body diagrams, one for each mass. 3.Write the Net Force Expressions for Each FBD.

HW: FAP#7 After you create each free body diagram, use your free body diagram to make an F net =ma expression in the x direction and in the y direction. Ex ` ` `` FNFN FgFg F AP F F AR F netx =F ap -F f -F AR =ma car-x-direction F nety =F N -F g =ma car y-direction

F#11 PULLEY’S & NEWTON’S 3 RD LAW For 1 & 2. Find M if a=-2 m/s 2 and a=2m/s 2 For 3 & 4. Find M if a is downward at 4m/s 2 and 2m/s 2 as the arrow shows 4 kg M 1. M 8kg kg M M a M M 2kg a 4. a a μ=0.1 no Friction