Simple Machines The six simple machines are: Lever Wheel and Axle Pulley Inclined Plane Wedge Screw Video

Simple Machines A machine is a device that helps make work easier to perform by: transferring a force from one place to another, changing the direction of a force, increasing the magnitude of a force, or increasing the distance or speed of a force.

The Lever A lever is rigid bar that is free to move about a fixed point. In use, a lever has both an effort (or applied) force and a load (resistant force). 3 parts of lever: Fulcrum (the fixed point) Input arm (the side of the lever you exert a force on) Output arm (the side of the lever that is doing the job)

Fulcrum is located in the middle. Ex: scissors

Load is between the fulcrum and the effort Load is between the fulcrum and the effort. **Used to lift heavy loads by using a much greater input arm. Ex: wheel barrow, can opener, hammer

Effort is between the fulcrum and load Effort is between the fulcrum and load. Ex: human forearm, stapler, tweezers

Wheel and Axle Consists of a large wheel rigidly secured to a smaller wheel or shaft, called an axle.

Pulley A rope that fits into a grove in a wheel Three types: Fixed- stationary (doesn’t move when you pull the rope) Movable – moves with the lifted object Pulley system- uses a combination of pulleys

Inclined Plane An inclined plane is an even sloping surface. The inclined plane makes it easier to move a weight from a lower to higher elevation.

Although it takes less force for car A to get to the top of the ramp, all the cars do the same amount of work. A B C

Wedge V shaped- 2 inclined plane Ex: ax

Screw An inclined plan wrapped around a cylinder

MA of an screw can be calculated by dividing the number of turns per inch.

Game

Efficiency Efficiency = the measure of how much work must be put into the machine than the work you get out. Input Force x Distance = Output Force x Distance However, some output force is lost due to friction. The comparison of work input to work output is called efficiency. No machine has 100% efficient due to friction.

Mechanical Advantage Input force (the force you apply) and the output force (force which is applied to the task) MA = output/input Output force > input force = mechanical advantage greater than one. Output < Input force = Less than 1 = less mechanical advantage