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Warm Up 7 10.27.11. Why should you choose an axe instead of a steel baseball bat to cut down a tree? (hint: Pressure=Force/Area). Applying Force - Pressure. The amount of force per unit of area is called pressure Pressure = force/area of application P=F/A
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Warm Up 7 10.27.11 Why should you choose an axe instead of a steel baseball bat to cut down a tree? (hint: Pressure=Force/Area)
Applying Force - Pressure The amount of force per unit of area is called pressure Pressure = force/area of application P=F/A (A is the area over which the forces act) Unit = Newtons per square meter = pascals (Pa)
Force SI unit – Newton; N A force needed to accelerate a 1 kg mass 1 m/s every second. 1kg*m/s2 = 1N A vector quantity
Free Body Diagrams, Why?! Calculating requires you to think about what is going on Drawing free body diagrams help you see Net Force
Free Body Diagrams • Is the object accelerating? • If Yes, Net Force ≠ 0 • If No, Net Force = 0 • What is the object on? • If in midair, Fair and Fgrav • If on something, Fnorm and Fgrav
Free Body Diagrams • How many and which way are applied forces going? • Is there Ffric? • If Yes, Ffric is opposite of Fapp
Fnorm Fapp1 Fair + Ffric Fgrav Diagram the forces on the car, traveling at a constant speed.
Fnorm Fapp1 Fair + Ffric What is my Fnet? Fgrav Diagram the forces on the car, accelerating to the left.
Determine the net force for each situation. www.physicsclassroom.com 0 N – balanced force 5 N, Left
Fnorm Fapp1 Fapp2 5 N 5 N Fgrav Create a free body diagram of the dog
Fnorm 5 N 5 N Fapp2 Fapp1 Where’s Ffric? Fgrav Create a free body diagram of the dog
Fnorm Fapp1 Fair + Ffric Fgrav Diagram the forces on the car, traveling at a constant speed.
Determine the net force for each situation. www.physicsclassroom.com 15 N, Up 0 N – object in equilibrium
Warm Up 8 10.28.11 • What were Galileo’s 2 main breakthroughs about motion?
Students who have not taken the Projectile Motion test need to take it by Wednesday afternoon or it will be a zero. • Last day for late work (including catapults) is also Wednesday.