Simple Machines
Elementary School
Definition
Basic devices that make work easier by changing the size or direction of a force, including the lever, pulley, wheel and axle, inclined plane, wedge, and screw. They do not reduce the total work but allow a task to be done with less effort.
Worked examples
A lever (crowbar) lets you lift a heavy rock with less force by pushing down on the long end.
The lever changes the direction of force and multiplies it, making the task easier.
An inclined plane (ramp) allows you to push a box up into a truck instead of lifting it straight up.
The ramp spreads the work over a longer distance, reducing the force needed at any moment.
A pulley system lets you pull down on a rope to lift a flag up the pole.
The pulley changes the direction of your pull, making it more convenient to apply force.
Common mistakes
- Simple machines reduce the total amount of work required. → Simple machines make work easier by reducing effort, but total work stays the same. Work is force times distance; machines trade off—less force means greater distance.
- A screw is not a simple machine because it looks complex. → A screw is a simple machine—it is an inclined plane wrapped around a cylinder. All six types (lever, pulley, wheel-axle, inclined plane, wedge, screw) are simple machines.
- Simple machines create energy to help you do tasks. → Simple machines do not create energy; they redirect or multiply force. Energy is conserved—machines only change how force is applied, not the total energy used.
Where you'll use it next
You'll apply simple machines when studying compound machines, mechanical advantage, and efficiency in physics, and when analyzing tools, construction, and engineering designs in technology and applied science courses.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026