Chapter Nine Simple Machines 9 1 Types of

Chapter Nine: Simple Machines Ø 9. 1 Types of Simple Machines Ø 9. 2 Mechanical Advantage Ø 9. 3 Levers in the Human Body

9. 1 Using Machines ØA machine is a device with moving parts that work together to accomplish a task. ØA bicycle is a good example.

9. 1 Using Machines ØThe input includes everything you do to make the machine accomplish a task, like pushing on the bicycle pedals. ØThe output is what the machine does for you, like going fast or climbing a steep hill.

9. 1 Forces in Machines ØA simple machine is an unpowered mechanical device, such as a lever.

9. 1 Review of work Ø Every process that is done by machines can be simplified in terms of work: 1. work input: the work or energy supplied to the process (or machine). 2. work output: the work or energy that comes out of the process (or machine).

9. 1 Review of energy ØA rope and pulley machine illustrates a rule that is true for all processes that transform energy. ØThe total energy or work output can never be greater than the total energy or work input.

9. 2 Mechanical advantage ØMechanical advantage is the ratio of output force to input force.

9. 2 Mechanical advantage ØMachines multiply forces. ØOne person could lift an elephant—quite a heavy load—with a properly designed system of ropes and pulleys!

9. 1 Mechanical Advantage mechanical advantage MA = Fo Fi Input force (N) Output force (N)