1. Simple Machines MAKE WORK EASIER TO DO! LEVERS, PULLEYS, INCLINE PLANE, SCREW, WHEEL AND AXEL, WEDGE

2. LEVERS A lever is a rigid bar that rotates about a fulcrum. There are three classes of levers. Each class depends on the position of the load, effort, and fulcrum.

3. FIRST CLASS LEVER In a first class lever, the fulcrum is between the Load Force (LF) and the Effort Force (EF). The Mechanical Advantage (MA) is an increase in force. Ideal Mechanical Advantage (IMA) is calculated by dividing the Effort Arm (EA) by the Load Arm (LA). (IMA= EA÷LA) *To determine to effort required for ALL simple machines, you divide the load force by the IMA!

4. SECOND CLASS LEVER In a second class lever, the LF is between the fulcrum and the EF. Like the first class lever, the MA is an increase in force and is calculated by dividing the EA by the LA. (IMA= EA÷LA)

5. THIRD CLASS LEVER In a third class lever the EF is between the LF and the fulcrum. Unlike the first and second class lever, the MA is an increase in the speed of the LF, not and increase in force. The IMA is still calculated by dividing the EA by the LA, but because it will take greater effort to move the LF, the IMA will always be less than 1. (IMA= EA÷LA) (IMA<1)

6. EXAMPLES OF LEVERS

7. PULLEYS A pulley is a wheel or a set of wheels used with a rope to change the direction and magnitude of a force.

8. IMA OF PULLEYS The IMA is directly dependent on the number of supporting ropes. You can count all the ropes then minus the one you are pulling down on. If you are pulling up, then you need to count it in the calculation! *The amount of rope required to move the pulley multiplies with the IMA.

9. TYPES OF PULLEYS

10. INCLINE PLANE An incline plane is a plane whose angle to the horizontal is less than 90 o.

11. IMA OF INCLINE PLANES IMA of incline planes is calculated by dividing the length of the slope by the height of the slope. (IMA=length of slope ÷ height of slope) This allows for the distribution of force over a greater distance.

12. SCREW A screw is an incline plane wrapped around a cylinder. It can be used to change the magnitude and/or the direction of a force.

13. IMA OF SCREWS To calculate the IMA of a screw you divide the circumference of the cylinder by the pitch (distance between threads).

14. WHEEL AND AXLE A wheel and axle is a large diameter wheel connected to a narrow diameter shaft. Depending on the location of the EF, the MA can either be an increase in output speed or magnitude of force.

15. WHEEL AND AXLE IMA To calculate the IMA of a wheel and axle you divide the radius of the wheel by the radius of the axle. When the EF is on the axle, the MA is speed in the wheel. When the EF is on the wheel, the MA is force on the axle.

16. WEDGE A wedge is a set of incline planes put back to back and they are used to push two objects apart or cut an object into pieces.

17. IMA OF A WEDGE To calculate the IMA of a wedge, you divide its length by its width.