Force & Motion Vocabulary List
force: a force is a push or pull on an object
net force: the combination of all of the forces acting on an object; think about a tug-of-war...
you have one side pulling and the other side pulling – two sets of forces on the rope!
balanced forces: when all of the forces acting on an object are perfectly balanced (equal);
to get this, you need forces countering each other, with the same strength; balanced forces
do not produce a change in motion
unbalanced forces: when the forces acting on an object are not countering each other with
the same strength, you get one force that is stronger than the other; unbalanced forces cause
a change in motion
newton: the unit we use to measure forces
motion: when an object changes places over time
speed: how fast something moves
velocity: how fast and in what direction something moves
acceleration: any change in velocity; this means you can accelerate if you change how fast
(the speed) or the direction and call it acceleration, because velocity includes both
friction: a force that tries to stop motion, caused by the uneven surfaces of one object or
substance rubs against the uneven surface of another object or substance
fluid: any material that can flow and that takes the shape of its container; liquids or gases
air resistance: a kind of friction that happens when air particles hit a moving object; it slows
objects moving through air down
mass: the amount of matter that something is made of
weight: a measure of the gravitational force put on an object.
gravity: a kind of force that causes attraction between two objects; the more massive the
objects, the stronger the force will be; the closer together the objects are, the stronger the
forces will be