1. AP PHYSICS MONDAY 14.11.03 STANDARDS: KINEMATICS 1D & 2D: BIG IDEA 3 Agenda: 1.Warm Up 2.Review HW #5 3.Understanding Friction Lab Homework Turn in HW Monday Warm Up A 3100 N Force is applied by the engine of a 1000 kg car to push it up a 12 degree incline. If the net acceleration of the car upwards at 0.5 m/s, what is the Force of friction on the car and what is the coefficient of friction between the car and the road? 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.11-12.9 Synthesize information from a range of sources into coherent understanding of a process, phenomenon, or concept,… Learning Goal: SWBAT calculate the coefficient of friction between a mass and a table.

2. AP PHYSICS TUESDAY 14.11.06 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.11-12.9 SYNTHESIZE INFORMATION FROM A RANGE OF SOURCES INTO COHERENT UNDERSTANDING OF A PROCESS, PHENOMENON, OR CONCEPT,… WHST.11-12.7: RESEARCH TO AID IN PROBLEM SOLVING Agenda: 1.Warm Up 2.Review HW 3.KAP #7 4.Friction Inquiry Homework FAP#7 Warm Up Learning Goal: SWBAT create net force expressions from free body diagrams The ball below is 6kg and rolls down the frictionless ramp. Air resistance is negilgable. What is the acceleration of the ball? 60°

3. AP PHYSICS WEDNESDAY 14.11.05 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.11-12.9 SYNTHESIZE INFORMATION FROM A RANGE OF SOURCES INTO COHERENT UNDERSTANDING OF A PROCESS, PHENOMENON, OR CONCEPT,… Agenda: 1.Warm Up 2.Review HW 1.Learning Goal: SWBAT find the coefficient of friction between the ramp and the cylinder Homework FAP #5 & FAP#6 Warm Up The ball below is 6kg, the coefficient of friction is 0.6 and air resistance is negligible. What is the acceleration of the ball down the ramp. 60°

4. AP PHYSICS THURSDAY 14.11.06 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.11-12.9 SYNTHESIZE INFORMATION FROM A RANGE OF SOURCES INTO COHERENT UNDERSTANDING OF A PROCESS, PHENOMENON, OR CONCEPT,… WHST.11-12.7: RESEARCH TO AID IN PROBLEM SOLVING Agenda: 1.Warm Up 2.Review HW 3.Continue Friction Lab Homework Friction Quiz Tomorrow Warm Up Learning Goal: SWBAT calculate the angle of slippage of an object on a ramp from your previously measured friction coefficient. Find the angle of a stationary object on a ramp if the mass is 3 kg and the coefficient of static friction is 0.7.

5. Agenda 1.Warm Up 2.Friction Quiz 3.Simple Pulley Homework FAP #8 Warm Up A skateboarder drags a 5 kg box at a constant speed and at an angle of 20 degrees to the horizontal. If the coefficient of kinetic friction is 0.27, how much Force will the skateboarder need to apply to maintain his/her speed.? Learning Goal: SWBAT draw a free body diagram of a simple pulley/box system. AP Physics Friday 14.11.07 Standards: 3a3 A force exerted on an object is always due to the interaction of that object with another object RST.11-12.4 Meaning of symbols, key terms, technical jargon Problem Solvers θ

6. 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

7. 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

8. 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.

9. 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 Calculate the coefficient of friction between the sled and the muddy surface of the slope. e. 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.

10. 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.

11. 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

12. 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