Simple Machines: Types, Force, and Examples

Physical Systems: Simple Machines

• Learning goals include identifying simple machines, explaining how they make work easier, and describing the relationship between input, output, and load force.
• Students should be able to correctly identify and describe the six types of simple machines.
• Examples of simple machines should be provided with appropriate terminology.
• Students should be able to describe how simple machines change the magnitude or direction of force.

Key Terms

• A simple machine requires a single force to work and is made of one or two parts.
• A fulcrum is a lever's pivot point.
• The load arm is the part of a lever that extends from the fulcrum to the mass being moved.
• The effort arm is the part of a lever that extends from the fulcrum to where a force is applied.
• Input force is the effort force applied to a lever.
• Output force is the force a lever applies to the load.
• Load force is what the input force must overcome to cause movement.

Simple Machines and the Physical Systems

• A simple machine is a device composed of only one or two parts needing only a single force to work, like a stapler.
• There are six simple machines: the inclined plane, the wedge, the screw, the lever, the wheel and axle, and the pulley.
• These can be categorized as related to the inclined plane (wedge and screw) or the lever (wheel and axle and pulley).

Inclined Planes, Wedges, and Screws

• An inclined plane is a tilted flat surface.
• Ramps and staircases are examples of inclined planes.
• A wedge is a modified inclined plane that moves back and forth with ease, like knives or an axe.
• A spiral staircase is an inclined plane wrapped around a central core.
• A screw is an inclined plane cut into a central core.
• The Archimedes' screw is used to lift water and move sludge, or ice.

Levers

• A lever is a rigid bar that pivots at the fulcrum.
• The load arm is the part of the bar between the fulcrum and the load.
• The effort arm is the part of the bar between the fulcrum and the effort.
• Input force is the force applied by the user.
• Output force is the redirected push the lever applies to the load.
• Load force is the force the user's input force overcomes, or resistance.
• Levers are divided into three classes.
• Class 1 levers have the fulcrum between the load force and the input force.
• Class 2 levers have the load force between the fulcrum and the input force.
• Class 3 levers have the input force between the fulcrum and the load force.

Wheel and Axles, Gears, and Pulleys

• Rotary motion is a part of many physical systems with turning motions.
• The turning motion is transferred through the use of wheels, pulleys, and gears.
• A crank is a modified lever that rotates around its fulcrum.
• A wheel and axle consists of a large diameter disk (wheel) attached to a small diameter shaft (axle).
• A small input force turns the axle into a larger output force.
• Sometimes a large input force on the axle is used to gain an advantage in distance, like a spinning top.
• Wheel and axle devices transfer rotary > rotary motion, rotary > linear motion, or linear > rotary motion.
• Gears are toothed wheels commonly made of metal or plastic.
• Gears speed up, slow down, or change the direction of motion.
• A gear train occurs when gears are used in combination with one another.
• Gears reduce input force or increase it, each with specific advantages and disadvantages.
• Pulleys can help lift heavy loads or change the direction of force.
• Pulley systems can contain fixed and moveable pulleys.
• A fixed pulley is attached to a rigid, non-moveable structure.
• A moveable pulley is not attached to a fixed structure.

Systems Evolve

• Learning goals include understanding how systems evolve over time, analyzing factors for changes in systems, and comparing historical/modern versions of systems.
• Students can explain at least two factors for system evolution.
• Students can describe how waste management systems have changed over time.
• Students can compare early telephone systems to modern cell phones.
• Students can discuss self-directed learning in education systems.

Vocabulary

• System: A set of connected parts forming a complex whole.
• Evolution: The gradual development of something.
• Waste Management: The collection, transportation, and disposal of garbage and other waste products.
• Landfill: A site for the disposal of waste materials by burial.
• Recycling: The process of converting waste materials into new materials and objects.

Introduction

• All systems change over time due to living conditions, social conditions, and new technologies.

Waste Management Systems

• Canadians produce about 31 million tonnes of waste each year.
• About 67% of waste is buried in landfill sites.
• Landfill is only one part of waste management, which includes recycling, hazardous waste drop-off, composting, incineration, and public education.

Telephone Systems

• Telephone systems have been around since the late 1800s, but have undergone many changes over the past 50 years
• Early telephones relied on physical mechanisms.
• Early phones had a spring-loaded hook and a rotary dial.
• In the 1960s, electronic touch-tone phones became widespread.
• Up until the 1980s, most telephones were connected by wires.
• Today's telephones are smaller, mobile, and have different uses, can transmit sound, printed messages, and photographs all over the world.

Education System

• Mary Ward Catholic Secondary School in Toronto is one of just two self-directed learning schools in Ontario.
• Social factors either ease / make more difficult changing a school system.
• The belief that students are more successful when they take responsibility for their own learning helps ease change.
• The belief that students should finish courses by the end of the traditional school year can make change difficult.

System Components

• The learning goals include understanding systems and their components, identifying inputs/outputs/side effects, and applying systems thinking.
• Success is defined by defining key terms, breaking down a systems, explaining inputs/outputs, and demonstrating systems thinking via analysis.

Vocabulary

• System: A group of interconnected parts working together for a specific purpose.
• Force: Any push or pull on an object.
• Input: The force, energy, or raw materials put into a system.
• Output: The task or service a system performs.
• Side effects: Unintended or undesired outputs of a system.
• Systems thinking: Considering the inputs, outputs, and side effects of systems.
• Subsystem: A smaller system within a larger system.
• Mechanism: A subsystem part that changes a force, energy, motion, or action into another

Introduction

• Physical and social systems vary in size and complexity.
• Smaller simple systems are can openers and school clubs.
• Larger complex systems are space shuttles and federal governments.

Breaking Down Systems into Subsystems

• Systems have smaller systems within them, called subsystems.
• Subsystems help perform a system's designed task.
• A handheld can opener has holding/cutting and turning subsystems.
• The GPS is a large, complex system that provides location information.
• A GPS has space, control, and user subsystems.
• The space subsystem has 24 satellites.
• The control subsystem has U.S. Air Force monitoring stations.
• The user subsystem is a receiver that uses signals from 3 satellites.

Breaking Down Subsystems into Mechanisms

• Subsystems contain mechanisms, which change one type of force, energy, motion, or action into another.
• In physical systems, forces make things move by push or pull, which causes a change.
• Mechanical systems have handless and cutting wheels that comprise the holding and cutting systems.
• Natural physical systems have subsystems and mechanisms too, for example the human digestive system contains organs.
• The human mouth acts as a mechanism for cutting and grinding food.

Building Up Systems into Industries

• Systems combine to create industries, which are combinations of physical and social systems.
• The communications industry includes all physical and social systems that produce media.

System Inputs and Outputs

• All systems (and subsystems) have inputs (forces, energy, raw materials) and outputs (tasks or services).
• The input of a can opener is hand force and its output is turning and cutting a lid.
• A bicycle's input is the rider's downward force and its output is movement.
• Gardens require water, sunlight, fertilizer, seeds, and pruning to have desired outputs.
• Ontario's health care has doctors, money, nurses, lab workers as inputs.
• The outputs include emergency operations, medicine, and grief counseling.

Side Effects and Systems Thinking

• Systems have desired and undesired outputs, the latter called side effects.
• Car use is an example with the side effects are air pollution, traffic, noise pollution, and habitat loss.
• Systems thinking involves how parts of a system work together and how systems affect their environment.
• Developing systems, thinking reduces side effects.