glossary

Glossary **Forces:** is a push or pull acting upon on object as a result of its interaction with another object.



**Contact forces:** Force that requires two pieces of matter to touch.



**Friction**: force of resistance to motion between two surfaces moving over each other.



**Non- Contact Forces:** Force that acts at a distance, three examples of non-contact forces are gravity, electric forces, and magnetic forces.



**Gravity:** is a force that holds things to the Earth´s surface and prevents things from floating off into the atmosphere.



**Acceleration:** rate at which velocity changes with time of both speed and direction.



**Speed**: is a measurement of how fast an object moves relative to a reference point. It does not have a direction and is considered a magnitude or scalar quantify.

**Inertia**: the resistence of any physical object to any change in its state or motion.



**Machine:** a tool that makes work easier.



 **Simple machine**: basic machines that include the lever, wheel and axle, pulley, inclined plane, wedge and screw.



**Lever:** It is a type simple machine in which a bar moves around a fixed point or support called fulcrum.

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Pulley.** It is a simple machine consisting of a rope or cabel that runs around a grooved wheel.



<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Wheel And axle.** It is a simple machine madre up of a circular object attached to a bar. This machine reduces the amount of force needed to do work.

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Inclined plane:** It is a simple machine that consists of a flat surface with one end higher than the other.

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Wedge:** It is a simple machine that can be made of one or two inclined planes. Some wedges, such as an axe, are made of two inclined planes placed back to back.



<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Screw:** It is a simple machine consisting of a smooth cylinder with a tiny inclined plane wrapped around it.

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Complex machine.** It is a machine made up of two por more simple machines that make your work easier to do.



<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Structures**. Are made up of several parts that support weight. The weight is distributed among the parts to make the structure strong and stable.



<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Mechanism:** consist of two parts or more operating parts working together. For example, a bicycle transmission ir made up of a large gear and smaller gear joined by a chain.

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">**Work**: force is used yo moved a load.

<span style="background-color: transparent; color: #000000; font-family: Arial; font-size: 14.6667px; text-decoration: none; vertical-align: baseline;">