1. AP PHYSICS MONDAY 15.02.23 STANDARDS: Agenda: 1.Warm Up 2.Collect HW 3.Review HW #7/ AP FRQ’s Homework Tap#3 Warm Up 3D.1&.2 change in momentum happens over time and is a vector pointing in the direction of the net force. I –Independent Resilient Individuals 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 Learning Goal: SWBAT demonstrate understanding of how elastic collisions affect the momentum of the object E-Effective Commuincators Find the torque given the following Force and radius vectors. 35° 20° F=40N r=5m

2. AP PHYSICS TUESDAY 15.02.24 STANDARDS: Agenda: 1.Warm Up 2.Collect HW up to Tap#2 3.Review Tap#3 4.Finish Torque Ruler Lab #8 Homework Tap#4 Warm Up If the 0.8 kg rod below is 4 meters long and divided equally into 10 segments, what is the torque experienced by the rod? What force is causing the torque. 3D.1&.2 change in momentum happens over time and is a vector pointing in the direction of the net force. I –Independent Resilient Individuals 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 Learning Goal: SWBAT demonstrate understanding of how elastic collisions affect the momentum of the object E-Effective Commuincators

3. AP PHYSICS WEDNESDAY 15.02.25 Agenda: 1.Warm Up 2.Center of Mass Notes 3.Center of Mass Activity #9 4.Center of Mass Practice Tap#5 Homework Tap #5 Warm Up Is this 0.8 kg metal tube that is 4m long balanced? If no, what is the net Torque? Standards: 4D net torque changes angular momentum of system I –Independent Resilient Individuals 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 Learning Goal: SWBAT determine the center of mass for different systems of objects through calculation & experimentation. P-Problem Solvers 4kg Fap=25 N

4. AP PHYSICS THURSDAY 15.02.26 STANDARDS: Agenda: 1.Warm Up 2.Stamp HW Stamp HW Stamp HW 3.Finish #9 Center of Mass Activity 4.Finish Tap#5 5.2 conditions for objects to be fully at equilibrium Homework Finish Tap#5 Warm Up Below is a meterstick. Find the center of mass of the following weights with the black dot representing the reference point. Where on the meterstick will the center of mass be? *** Together lets compare the torque at the center of mass with the Sum of the Torques. *** Standards: 4D net torque changes angular momentum of system I –Independent Resilient Individuals 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 Learning Goal: SWBAT find the center of mass of systems of objects. P-Problem Solvers 8kg 2kg

5. AP PHYSICS FRIDAY 15.02.27 STANDARDS: Agenda: 1.Warm Up 2.Review of TAP#5 postponed until Monday 3.Variable Torque Hinged Joint Paper Lab Activity. Homework TAP #6 Warm Up Find the Net Torque on this multi- mass system by finding the Torque at the center of mass. Standards: 4D net torque changes angular momentum of system 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 Learning Goal: SWBAT analyze complex scenarios involving Torque in order to find unknowns. P-Problem Solvers 8kg 2kg 8kg 2kg 8kg Each mark on the ruler is 10 cm. Remember to assume that each individual mass is concentrated at one point at its center.

6. TAP#2 1.(1) The nests built by the mallee fowl of Australia can have masses as large as 3.00x10 5 kg. Suppose a nest with this mass is being lifted by a crane. The boom of the crane makes an angle of 45.0° with the ground. If the axis of rotation is the lower end of the boom at point A, the torque produced by the nest has a magnitude of 3.20x10 7 Nm. Treat the boom’s mass as negligible, and calculate the length of the boom. 2.(3) A meterstick of negligible mass is fixed horizontally at its 100.0 cm mark. Imagine this meterstick used as a display for some fruits and vegetables with record-breaking masses. A lemon with a mass of 3.9 kg hangs from the 70.0 cm mark, and a cucumber with a mass of 9.1 kg hangs from the x cm mark. What is the value of x if the net torque acting on the meterstick is 56.0 Nm in the counterclockwise direction? A.F=100 N r=50m τ=? B. F=20 N r=20m θ=30° τ=? C. F=10N r=4N θ=40° r F θ D. F=10N r=4N Φ=40° r F Φ

7. TAP#3 TORQUE& EQUILIBRIUM A. F=6N r=8N θ=20° F θ r m rod g F ap B. F ap =20N l=10m r=3m τ net =? m rod =5kg m block =2kg l r 1.A uniform meterstick of mass 0.20 kg is pivoted at the 40 cm mark. Where should one hang a mass of 0.50 kg to balance a stick? -- 36 cm 2.A meterstick of negligible mass has a screw drilled in it at the 0.60 m mark so it is free to spin. If the meterstick is stuck into the wall and a 2.0 kg mass hung at the 0m mark while you are holding up the other side, what is the magnitude of the net torque on the meterstick about the fulcrum immediately after you release the meterstick? r

8. TAP #4 TORQUE WORKSHEET PROVIDED TO YOU TAP#5 CENTER OF MASS

9. #9 CENTER OF MASS LAB ACTIVITY 2. Take a 20g and 40g mass. If the pivot point is at the 50 cm mark on the ruler and the 20g mass is placed at the 70 cm mark, where should you put the 40g mass to make the center of mass hit the pivot point. Calculate, then check your work by testing out your calculated position. 3. Take a 10 g mass. Place the 10g mass on the 80 cm mark. Where should you make the pivot point so that it touches the center of mass and the ruler balances? Calculate then test with a ruler and masses. 1. Find the center of mass of a 100 g mass at the 75 cm mark and a 200 g mass at the 25 cm mark. Will there be a net Torque associated with this center of mass? Calculate the net Torque at the center of mass. 4. A 100 g mass is at the 90cm mark on a ruler that pivots at the 50 cm mark. A 500 g mass is at the 30 cm mark on the same ruler. Where would a 200 g mass need to be placed to make the center of mass hit the 50 cm mark. Calculate then verify.

10. #10 TORQUE ON A HINGE JOINT Theory Torque is a force at a radius. Specifically a torque (twist) is caused when a force is applied perpendicular to a radius. The Greek letter τ, tau, is used for torque. Torques can act clockwise and counterclockwise and thus torque is a vector. The vector sum of all the torques on a system is called a net torque. The formula for any single torque is τ=r x F or |τ|=r F perpendicular where only the perpendicular component of the force causes a torque. Apparatus Details The set up illustrated above is a system of variable torque. However, since rotational will not occur, the net torque will be 0 in all cases. For simplicity, we will agree to assign the hinge (pivot) as the zero point. On the diagram at right, draw labeled vector arrows for the three forces causing torques: the weight of the mass M, the weight of the plank m, and the Tension T. There is another force on the plank; it is the normal force from the hinge. Can you convince yourself that (if you were to draw it) it would point up and to the right? Both weights’ torques point downward (clockwise), the tension’s point upward (counterclockwise). However, the tension is not straight up. Since only perpendicular force can cause a torque, draw and label sine and cosine components of the tension. Label each component. Questions i According to the figure on the left, what is the torque from the hanging mass, M ii.What is the torque from the plank’s mass? iii.What is the torque from the rope’s tension? iv.Can you prove that the normal force provides no torque? v.Which is the larger? The torque from the two masses, or the rope’s? Explain. Spring Scale Hinge T m M R L h

11. TAP#6 TORQUE ON A HINGE JOINT This is a setup that may be given on the AP Test so lets get to know it. 1.Find the Center of Mass of this 2 mass system. 2.Find the Torque caused by the the uniform density hinged rod. 3.Find the Torque caused by the hanging mass. 4.Find the Torque caused by the Rope. 5.Find the angle between the rope and the hinged rod 6.Find the component of Tension that causes Torque 7.Find the component of Tension that is wasted (that does not produce Torque) 8.Find the Tension reading on the spring scale. 9.Give yourself a pat on the back for finishing!!! Spring Scale Hinge T 500g 40cm 50cm 30cm A. 80g