1. Simple Machines Two classes 1.) those in which there is an equilibrium of torques lever Pulley Wheel and axle 2.) those dependent on the vector resolution of forces inclined plane wedge screw

2. Lever a rigid object that is used with a fulcrum or pivot point multiplies the mechanical force (effort) that can be applied to resistance force (load) multiplies the distance and speed at which the opposite end of the rigid object travels. Ideal Mechanical Advantage = length of input (effort) arm length of output (resistance) arm IMA = L in L out

3. Levers can be used to exert a large force over a small distance at one end by exerting only a small force over a greater distance at the other

4. Levers—a bar free to pivot or turn on a fixed point Fulcrum is the fixed point the lever pivots on Input arm=distance from the fulcrum to the point where the input force is applied Output arm=distance from fulcrum to the point where the output force is exerted by the lever The output force depends on the lengths of the input and output forces. Output arm>Input arm then output force is less than input force If Output arm shorter than Input arm then output force is greater than the input force

5. Work in = Work out (effort )(effort arm) = (resistance )( resistance arm)

6. Provided the proper application of the fulcrum in a lever almost anything can be balanced as indicated by this demonstration

7. 3 Classes of Levers Variations in the relative locations of the fulcrum, the load and the force: Class 1: The fulcrum is located between the force and the load a crowbar, a pair of scissors or a seesaw Class 2: The load is situated between the fulcrum and the force a wheelbarrow or a nutcracker Class 3: The force is applied between the fulcrum and the load a pair of tweezers or the human mandible

10. If Tony weighs 60 N and sits 3 m from the fulcrum on the teeter-totter, how far does Jessie have to sit from the fulcrum to lift him if she weighs 50 N? Work in = Work out (effort )(effort arm) = (resistance )( resistance arm) (50 N)( effort arm) = (60 N)( 3 m) effort arm = (60 N)( 3 m) / (50 N) Distance = 3.6 m