Simple Machines Do now: Clear your desk except for ISN and pencil. BE READY to take a few notes. BE READY to take a few notes.

Simple machine- a device that does work with only one movement. -Machines make work easier by changing the force you exert in size, direction or both. -Simple machines try to move something that resists being moved. (Ex: friction or gravity)

Make work easier to do by: Increasing the size of an applied force Changing the direction of an applied force Changing the distance over which a force acts There will always be a trade-off!!!

There are 6 types of simple machines. All are variations of lever or inclined plane. LeverInclined plane 1. Lever4. Inclined plane 2. Pulley5. Screw 3. Wheel and6. Wedge axle

simplemachines.htm

What goes in… Input is also called “effort:” -Effort force is the force applied to a machine -Effort distance is the distance across which the effort is applied What comes out… Output is also called “resistance:” -Resistance force is the force exerted by a machine -Resistance distance is the distance across which the machine applies effort

1.Lever- a bar that is free to pivot or turn about a fixed point. - Fulcrum- fixed point of a lever -Effort arm- part of the lever where the effort force is applied -Resistance arm- part of the lever where there is resistance

FULCRUM LOAD EFFORT Fixed point about which the lever rotates The mass being lifted by a lever Force used to lift the load Review: Force is a push or a pull on an object, and is measured in Newtons

There are different types of levers. -1 st class Effort ▲Resist Ex: seesaw scissorspliers

-2 nd class Effort Resist ▲ Ex: Stapler Wheelbarrow Nail clippers

-3 rd classResist Effort ▲ Ex: Tweezers Swinging a bat Fishing rod

2. Pulley- a grooved wheel with rope running along the groove. There are 3 types of pulleys 1.Fixed- the pulley is stationary 2.Movable- the pulley can move 3.Block and tackle- Fixed and movable put together

-Fixed -Movable -Block & Pulley Pulley Tackle Pulley

3. Wheel and axle- 2 wheels of different sizes that rotate together. -Always travel in a circle. -Effort force is applied to the larger wheel while the smaller wheel (axle) exerts the resistance force.

Example of a wheel and axle

Wheel and Axle A simple machine that is a wheel attached to a shaft, or axle.

4. Inclined plane- a sloping surface used to raise objects. Ex: a ramp. Using a ramp, you cover more distance but exerts less force.

Inclined Plane A simple machine that is a sloping surface, such as a ramp.

5.Screw- an inclined plane wrapped in a spiral.

6. Wedge- an inclined plane with 1 or 2 sloping sides. -Wedges are moving inclined planes. Ex: Knife or ax blade.

Wedge A simple machine that has a thick end and a thin end. A wedge is used to cut, split, or pierce objects or to hold objects together.

Amanda uses a wheelbarrow to lift a load of bricks. The bricks weigh 600 N, which is more than Amanda could normally carry. However, with the wheelbarrow, Amanda can lift the bricks with as little as 120 N. What is the mechanical advantage of the wheelbarrow?

Marshall wants to remove a tree stump from the ground. To do this, he puts one end of a long beam under the stump and puts all of his weight on the other end. His weight is just enough to lift the stump. The stump weighs 400 N. Marshall weighs 250 N. What is the mechanical advantage of the lever Marshall is using?

A 5-meter ramp lifts objects to a height of 0.75 meters. What is the mechanical advantage of the ramp?