# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
F
Fahrenheit scale: A temperature scale still used in the United States.
fault: A fracture where there is movement parallel to the fracture surface.
field force: A force that acts between two objects at a distance as one object sets up a force field that affects the other object. There are different types of field forces: gravitational, magnetic, electric and nuclear.
filtrate: A substance that passes through a filter during filtration.
filtration: A technique in which one part of a mixture (usually the liquid part) passes through the holes of a barrier leaving the rest of the mixture unable to pass through.
flammable substance: A substance that will burn.
flexibility: A measure of a substance’s ability to bend or be twisted.
flocculation: Small suspended particles coming together to form larger, heavier particles, which are usually insoluble.
flotation: A separation technique in which a lighter substance is skimmed off the top of a liquid after undergoing a reaction that involves the substance sticking to bubbles of air.
fluid friction: A friction force that tends to slow an object moving in a fluid such as water or air. Air resistance is a type of fluid friction.
focus: The point at which light converges.
force: A push or a pull. There are contact forces and field forces.
formant frequencies: The resonant frequencies of the human voice.
forward reaction: The forward process of an equilibrium reaction. New substances are formed after bonds break in a chemical reaction.
fossil: The remains or traces of prehistoric life preserved in rocks from Earth’s crust.
freezing: A change of state from a liquid to a solid.
frequency: The speed at which something repeats itself. For example, a ruler may make five vibrations per second; the frequency is then said to be five vibrations per second or 5 Hz (hertz).
friction force: A force that tends to slow an object down or keep it at rest. There are different types of friction: static, rolling or sliding, and fluid.
fulcrum: A pivot in a lever.
fuse: An electric circuit component that has a low melting point. A large current through a fuse will melt it, thus causing an open circuit.
fusion: The amalgamation of two nuclei.