Physical Systems Simple Machines What are simple machines

Physical Systems: Simple Machines What are simple machines and how are they useful?

Simple Machines A simple machine is a device, composed of only one or two parts, that requires a single force to work. The stapler works by applying a single downward force at its open end. Like the stapler, the mechanisms of most physical systems are made of one or more simple machines that work alone or together to make physical tasks such as nailing, cutting, throwing, carrying, chopping and prying easier to do.

Simple Machines There are six simple machines: the inclined plane the wedge the screw the lever the wheel and axle the pulley These simple machines can be categorized into two groups those related to the inclined plane (the wedge and the screw) those related to the lever (the wheel and axle and

Inclined Plane Makes lifting easier. The force needed to push an object up an inclined plane is less than the force needed to lift it straight up. Examples: highway or sidewalk ramp, stairs, inclined conveyor belts, switchback roads or trails Ideal Mechanical Advantage

Wedge Pushes materials apart, cuts things. You must apply a force to a wedge for it to work. As the wedge is pushed into the object, the object splits. Examples: axe, doorstop, chisel, nail, saw, jackhammer, bulldozer, snow plow, horse plow, zipper, scissors, airplane wing, knife, fork, bow of a boat or ship.

Screw A screw is a cylinder with an inclined plane wrapped around it. Turns rotation into lengthwise movement Takes many twists to go a short distance Holds things together Examples: screws, bolts, clamps, jar lids, car jack, spinning stools, spiral staircases

Lever Makes lifting weight easier by using a fulcrum to redirect force over a longer distance. The load arm is the part of the bar between the fulcrum and the object (load) you want to move. The effort arm is the part of the bar between the fulcrum and where the effort is applied Examples: see-saw, dump truck, broom, crane arm, hammer claw, crow bar, fishing pole, screwdriver, bottle opener. fulcrum Effort arm Load arm

Classes of Levers are divided into three classes: Class 1 levers: the fulcrum is between the load force and the input force. Class 2 levers: the load force is between the fulcrum and the input force. Class 3 levers: the input force is between the fulcrum and the load force.

Wheel and Axle Makes it easy to move things by rolling them, and reducing friction. You can apply force on the wheel to turn the axel or apply force on the axel to turn the wheel. Examples: car wheels, windmill, rolling pins

Pulley Makes lifting things with a rope easier by redirecting force and the addition of additional pulleys. As you pull a line over the wheel, you move the load. Examples: flag pole, elevator, sails, fishing nets, clothes lines, cranes, window shades and blinds,

Gear A gear is a modified wheel and axle. Gears are toothed wheels, most commonly made of metal or plastic. They are used to speed up or slow down motion, or to change the direction of motion.

Wedge Pushes material apart, cuts Wheel and Axle Makes it easy to move things by rolling them, and reducing friction Lever Helps lift heavy weights using longer distances Inclined Plane Makes it easier to move objects upward; a longer path, but easier lifting Screw Turns rotation into lengthwise movement Pulley Makes lifting heavy weights easier by redirecting force

CHECK YOUR LEARNING 1. Which of the six simple machines relates the most to your everyday life? Explain. 2. Complete the following table Simple Machine Example How Society Uses it to Make Life Easier