Levers are simple machines used to lift or move large loads by applying force to one end. Examples of levers are hammers, crowbars and bottle openers. A project involving levers could be to determine the relationship between the distances from the effort arm and load to the fulcrum, which is the pivot point, and the force required to move a given load. The effort arm is the section of the lever from the fulcrum to the point the effort is applied. Students alter the distance between the pivot and the load or effort arm while applying the same force every time at the effort arm and recording the outcomes. Students will discover that the longer the effort arm, the less force is required to move the same load using the lever.
Inclined planes are slanted surfaces such as ramps used for lifting objects. The ease of work depends on the angle of inclination of the plane. Using small angles requires less effort as opposed to larger ones. A project to determine the relationship between the effort required to raise a certain load and the angle of inclination can easily be set up using a ramp and a stage. Students can alter the angle of inclination by moving the point of the ramp touching the ground closer or further from the stage while noting down the effort required to raise the same load at different angles.
Pulleys are simple machines used to lift heavy loads. They are made of belts, ropes or chains wrapped on a wheel and work by changing the direction of a force. A project to compare fixed, movable and combined pulleys would aid students to determine which of the three is most efficient. Fixed pulleys require more force to lift an object than all the other pulleys; movable and combined pulleys make work easier, with the latter as the most efficient.
Work is defined as the product of the force exerted on a body and the distance it covers. For any simple machine, both the force at the effort and the load move; hence, work is done. Therefore, the work done at the effort and at the load is calculated by finding the product of the respective forces and the distances they cover. The efficiency of a machine is calculated by dividing the amount of work done by the force at the effort--the input of the machine--by the work done by the force at the load--the output of the machine. The quotient is then multiplied by 100 percent. The final product is the efficiency of any machine expressed as a percentage. Students can compare the efficiency of different types of simple machines in this project.