Science Terms D-G

a unit of measure for the relative intensity of sounds

the celestial coordinate similar to that of latitude on the Earth. Declination measures how many degrees, minutes, and seconds north or south of the celestial equator an object is.

a fan-shaped deposit of material at the mouth of a river

the mass of a substance for a given unit volume. A common unit of density is grams per milliliter (g/ml).

the change in position of an object, computed by calculating the final position minus the initial position. Common units of measure are meters (m).

a boundary between two of the Earth’s plates that are moving away from each other

contains all genetic material for an organism. The smallest units of DNA are called nucleotides.

the apparent path of the Sun across the sky over the course of a year

the energy due to an object’s position within an electric field

a light wave that has an electric field component and a magnetic field component. An electromagnetic wave does not require a medium to travel through.

the force that exists between particles due to their charge. Particles of like charge repel, particles of unlike charge attract.

the smallest entity that has distinct chemical properties. It cannot be decomposed by ordinary chemical reactions.

a geometric shape that is formed when a plane intersects with a cone. In this case, the plane intersects the cone at an angle, so that a shape similar to a circle but stretched in one direction is formed. The orbits of the planets around the Sun represent ellipses.

an organelle that is used to transport proteins throughout the cell

the ability to do work or undergo change. Kinetic energy is the energy of motion, while potential energy is stored energy.

smaller circles on which the planets traveled around the Earth in the geocentric model of the solar system. Epicycles were used to explain the retrograde motion of planets and help make the predicted positions of the planets match the observed positions.

a state at which the forward and reverse reactions proceed at the same rate

the distance from a focal point to a mirror or lens

that which acts on an object to change its motion; a push or pull exerted on one object by another. Common units are newtons (N).

an object in one-dimensional motion that is only acted on by the force of the Earth’s gravity. In this case its acceleration will be -g or g downward.

the number of cycles or repetitions per second. Frequency is also often measured as the number of revolutions per second. The common units of frequency are hertz (Hz), where one hertz equals 1 cycle/second.

the force that acts parallel to surfaces in contact opposite the direction of motion or tendency of motion

a group of atoms that give a molecule a certain characteristic or property

a process used in laboratories to determine the genetic makeup of DNA strands. This process involves the movement of chromosomes through a gel from one pole to the other. Magnetism is used to pull the chromosomes through the gel.