Forces and motion vocabulary: 18 terms with definitions

Speed in a given direction, such as 30 miles per hour north.

How fast velocity changes: speeding up, slowing down or turning.

Mass times velocity; the more momentum a moving object has, the harder it is to stop.

An object's tendency to keep doing what it is doing, staying still or moving, unless a force acts on it.

A force that resists motion between two surfaces rubbing together.

The force that pulls objects toward each other, such as things falling to Earth.

The unit of force, named after Isaac Newton, whose three laws of motion describe how forces move objects.

A push or a pull.

The amount of matter in an object, measured in grams or kilograms.

The pull of gravity on an object's mass; you would weigh less on the Moon, but your mass would stay the same.

How far something travels in a given time, such as 60 miles per hour.

How far an object travels.

The energy an object has because it is moving.

Stored energy, such as in a stretched spring or a book on a high shelf.

The ability to do work or cause change.

The unit of energy and of work.

A disturbance that carries energy from place to place, such as sound or light.

The number of waves that pass a point each second, measured in hertz.