Simple Machines in your world!

Simple Machines in your world! Imagine… • eating soup without a spoon • hauling dirt without a wheelbarrow • opening a door without a doorknob …That is what life would be like without simple machines.

Machines are not limited to the complicated devices such as cars, computers, and airplanes! • A machine is any device that makes work easier. • They make work easier by placing forces where we want them, by moving things faster, and by making forces larger.

Friction Review Frictionis the force we feel when things rub against each other The more things are pushed together, the more friction there is It is the force that opposes motion.

Friction Review Friction slows down the movement of things and turns motion into thermal energy (heat). When you rub your hands together you can feel the thermal energy produced. The mucus from aslug will decrease friction as the slug slides along the ground.

Simple Machines The purpose of a simple machine is to A. increase the speed of work B. change direction the force is acting in C. increase Mechanical Advantage - a machine’s ability to multiply input force

Presenting the 6 simple machines:1. LEVER2. INCLINED PLANE3. WEDGE4. SCREW5. WHEEL AND AXLE6. PULLEY

Inclined Plane: • A simple machine with no moving parts. • It increases the distance the object moves, but it decreases the amount of force needed to move it. • It is simply a straight slanted surface. • An example - a ramp, roadways, slide, stairs

Wedge: • An inclined plane that moves. • Most are made of TWO inclined planes. • Examples: • ax • knife • and zippers!

Screw: • An inclined plane wrapped around a central bar to form a spiral. • A screw increases the distance which decreases the force needed. • Examples: • Screws • Jar lids

Lever: • An arm that “pivots” (or turns) around a fixed point • The fixed point is called the fulcrum. • A lever increases the distance to decrease the force required. • Examples: • seesaw • wheelbarrow • fishing pole

Wheel and Axle: • A simple machine made up of 2 circular objects of different sizes. • The wheel is the larger object and turns about the small object, (the axle). • Because the wheel is larger than the axle, it moves a greater distance. • Examples: • roller skates • doorknobs

Pulley: • A rope, belt, or chain wrapped around a grooved wheel • Works in 2 ways: • changes the direction of the force • or • changes the amount of force • Examples: • flagpole • sails on a sailboat

So What?????? • Like you heard at the beginning, machines make work easier. The measure of how much easier is called the mechanical advantage. • It is important to note that the work that comes out of a machine is never greater than the work put into a machine. In fact, machines actually require more energy to do the same job, even though they make the job easier! • Most of the machines we use today are compound machines - two or more simple machines working together!

Simple Machines in your world!