Simple Machines Study Guide



1.  Force:  any push or pull


2.  Gravity:  the attraction or pulling force between objects and the Earth.


3.  Friction:  the force that slows down or stops objects in motion


4.  Simple machine:  a machine with few or no moving parts.  There are six:  lever, screw, wheel and axle, pulley, inclined plane, and wedge.


5.  Compound machine:  a machine made of two or more simple machines.  Examples

      Include a can opener, a bulldozer, an elevator, etc.


6.  Fulcrum:  the point where a lever rocks back and forth


7.  Screw:  an inclined plane wrapped around a post; it’s used to hold things together.


8.  Wedge:  two inclined planes together; it is wide at one end and pointed at the other.  It is used to split or cut things apart.


9.  Energy:  the ability to do work


10.  Work:  occurs when a force moves an object over a distance; examples, running,

       Kicking a ball, moving furniture, the wind pushing a sailboat, etc.  No work is being done sitting still watching TV, pushing against something that won’t move, etc.


11.  Recycling:  making trash into something new instead of throwing it away:  items that can be recycled include glass bottles, some plastics, aluminum, newspapers, etc.


12.  Natural resources:  things found in nature that people can use:  trees, water,

        Metals, good soil, stone for building, etc.



1.  The amount of force needed to move an object depends on the object’s mass. Heavier things require more force to move them than lighter things do.  Dragging or pulling a heavy object takes less force than lifting it.


2.  Rough surfaces cause more friction than smooth ones.  Rough surfaces can be smoothed out by adding water, oil, or soap to the surface.


3.  Friction is needed to do most activities safely.  For example, tires with heavy or deep tread stop more easily on snow and slush than do smooth tires.  We couldn’t even walk without the aid of friction, or drive, or run.


4.  To decrease the amount of force needed to lift a load with a lever, move the fulcrum closer to the load.

5.  The longer the inclined plane is, the less steep it is.  The less steep it is, the less force is needed to move an object up it.  But the less steep it is, the longer the distance is to be traveled.


6.  Be able to tell which simple machines are in common household items.  For

      Example, a doorknob is a wheel and axle.  An ax is a wedge and a lever.


7.  There are many sources of energy.  Some are renewable and some are not.                Children need to know that renewable means that they can be produced again and again.  Nonrenewable means that once they are used up, they are gone forever.

Renewable energy sources:  wind, water, solar, wood, and geothermal.

Nonrenewable energy sources:  coal, oil, natural gas, and the elements used for nuclear energy.  Oil, coal, and natural gas are also called fossil fuels.

Wood is a renewable source, but can become nonrenewable if we burn more trees than we can grow.  Likewise with water.


8.  Nonrenewable sources of energy need to be conserved, or used wisely, or we will run out of them.  Ways of conserving energy are turning out lights when they’re not needed; turning down the thermostat at home; making fewer trips in the car to save gasoline; walking or riding a bike instead of riding in a car, etc.  Think of some more.


9.  Types of energy:  heat, light, chemical, sound, and motion, electrical, nuclear


10.  Many products are made from natural resources:  paper comes from trees, glass is

Made from sand, plastic comes from oil, soda cans are made from aluminum, etc.