1. Chapter 4: Machines and Mechanical Systems
4.1 Forces in Machines

2. Mechanical Systems and Machines
Machine: a device with moving parts that work together to accomplish a task
Example: a bicycle
Machines are designed to do something useful
Machines have an input and an output
Input: includes everything you do to make the machine work
Output: what the machine will do for you

3. Six Types of Simple Machines

4. Simple Machines Simple machine: an unpowered mechanical device
They work by manipulating forces
Most machines today are combinations of simple machines
Bicycle: wheels and axles, levers, and gears
Complex machine: a machine with many different simple machines put together

5. Mechanical Advantage Simple machines work by changing force and motion
Force: an action that has the ability to change motion
Mechanical advantage: the ratio of output force to input force
Remember: input is what you do to the machine, output is what the machine does for you
MA = Fo Mechanical Advantage = Output
Fi Input

6. Simple Machines in the Human Body
The human body is made completely of simple machines
Joints = levers
Hips/Shoulders = ball and socket
Anything else you can think of?