Chapter 15 : Simple and Compound Machines
Topics covered in this snack-sized chapter:
A machine is a tool that consists of one or more parts, and uses energy to achieve a particular goal.
Machines are usually powered by mechanical, chemical, thermal, or electrical means, and are frequently motorized.
Machines do not reduce the amount of work needed to perform a task; they reduce the effort needed from the user.
A simple machine is a mechanical device that changes the direction or magnitude of a force.
In general, they can be defined as the simplest mechanisms that provide mechanical advantage (also called leverage).
Can take the force exerted by the individual and redirect it
Can turn a small effort or force into a larger force (mechanical advantage)
Can magnify the distance that a force acts on
Simple Machines Work in One of 3 Ways
- Is a narrow beam that rotates around a single point called the fulcrum
- By placing an object to be moved, called the load, at one point on the beam and by applying an effort at another point the object can be moved more easily
- Device designed to reduce the force needed to raise an object.
- For example, pushing a load up a ramp onto a platform requires less force than lifting the load onto the platform.
- Screw is an inclined plane wrapped in a spiral around a shaft.
- Pulleys is a wheel over which a rope or belt is passed for the purpose of transmitting energy and doing work.
Wheel and Axle
- An axle is a rod that goes through the wheel to create a wheel and axle machine
- Wheels and Axles are used to move and lift objects
A compound machine consists of two or more simple machines put together.
In fact, most machines are compound machines.
Compound machines can do more difficult jobs than simple machines alone.
Their mechanical advantage is far greater, too.
- Some examples are: cars, wagons, doorknobs, pencil sharpeners, and bikes
Types of Compound Machines
There is a huge variety of compound machines available to assist with a large number of tasks.
Several examples of compound machines include: bicycles, pliers, wheelbarrows and scissors.
In bicycles, the pedals and wheels form cooperating wheel and axle systems, the brakes are levers and the parts are held together with multiple screws.
Pliers are constructed with multiple levers. A wheelbarrow is a combination of a lever and wheel and axle. Scissors consist of two pivoting levers.
A simple machine is what it says; it's a very simple machine, made up of only one simple machine, such as a screw or a lever.
A complex machine is more than one simple machine working together, instead of working alone.
The simple machine is one part.
The complex machine is made up of different- different parts
A simple machine is used to make work easier.
A compound machine is two or more types of simple machines together.
A simple machine is either a: lever, screw, incline, pulley, wheel and axle, and gear.
A complex machine is made up of more than one simple machine.