| A | B |
|---|
| balanced forces | the forces acting on an object that cancel each other out so that the object is either not moving (stationary) or moving at a constant speed |
| resultant force | the size of the overall force acting on an object |
| *reaction force | since forces always occur in pairs, every action is accompanied by a reaction of equal magnitude but opposite direction |
| upthrust | the force acting upwards on an object in flight or in water |
| density | the mass of a measured volume of any substance |
| *Archimedes' Principle | —”The upthrust acting on an object is equal to the weight of the fluid displaced by object.” |
| mass | a measure of the amount of matter in an object; measured in grams or kilograms |
| density formula | density = mass / volume |
| fluid | a substance that can flow, i.e. a liquid or a gas |
