Simple machines study guide

Know these simple machines and how they can make work easier.

Wheel and Axle

Inclined Plane:

A sloping surface, such as a ramp. With an inclined plane, things can be moved from a lower place to a higher place, or vice versa, such as loading and unloading a moving truck. Objects need to be moved a greater distance than if lifted straight up, but it less force is needed.

Wedge:

A wedge is two inclined planes joined back-to-back. Wedges are used to split things, such as using a knife or axe.

Pulley:

A pulley is a wheel with a groove for a rope or belt. Pulling down on the rope can lift at nobject attached to the rope. An example would be a flag pole, crane or mini blinds.

Wheel and Axle:

One or more wheels connected to an axle. When the axle is turned, the wheel moves a greater distance than the axle, but less force is needed. Examples would be a round doorknob, scooter, or wagon wheels.

Screw:

A screw is an inclined plane wrapped around a shaft or cylinder. The screw holds things together when twisted along its thread. Some examples are a light bulb or jar lid.

Lever:

A lever is a straight rod that pivots on a point knows as a fulcrum. Force on one end of the lever results in motion on the other side of the fulcrum. Some examples are seesaws, bottle openers, and brooms.

Compound machines:

A bike is compound machine.

  • Screws are used to hold the pieces together.
  • The wheel of a bicycle is a wheel and axle.The pedals are also examples of this simple machine
  • The gear shifts and brake handles are levers.

A manual can-opener is a compound machine:

  • The handle you turn to make the can rotate is a wheel and axle.
  • The two long arms that clamp the can securely make a lever.
  • The circular wheel that cuts the can lid is sharpened to make a wedge.
  • It is held together by screws

A stapler is a compound machine:

  • The two parts that pivot on the end make a lever.
  • The staples pierce paper, making them wedges.
  • It is held together by screws.

Important concepts to know:

Force—a push or a pull

Work- the measure of force it takes to move an object a certain distance.

Motion- a change in position

Speed- the measure of how fast something moves over a certain distance

Gravity- the force that pulls objects towards each other. The more mass two objects have, the more gravity pulls them toward each other. The Earth has a large mass, so the pull between the Earth and object is large as well. The moon has less mass, so the pull of gravity is less on the moon.

Weight- the measure of the pull of gravity on an object. Weight can change depending on the pull of gravity. So on the moon, you weigh less than you do on Earth. Hooray!