circumference

Energy is the power that comes from things like electricity, coal, or the sun to make machines work or provide heat. It also describes the physical and mental strength that people have to be active and do things.

Gravity is the natural force that pulls objects toward each other, especially toward the center of the Earth. It is what makes things fall to the ground and keeps us from floating away into space.

Friction is the force that happens when two surfaces rub against each other. It makes it harder for things to move and can create heat.

Inertia is the tendency of an object to stay still or keep moving in the same way unless a force changes it. In a general sense, it also refers to a lack of energy or a desire to stay unchanged.

Frequency is how often something happens in a certain amount of time. In science, it describes the number of times a wave or signal repeats every second.

Atomic relates to the very small parts called atoms that make up everything in the world. It is often used to describe science, energy, or very small things.

A substance, usually a liquid, that is used to dissolve another substance to create a mixture. In science, it is the part of a solution that is present in the largest amount.

A reduction is when something becomes smaller in size, amount, or importance. In science, it can also mean a chemical reaction where a substance gains electrons.

Organic chemistry is the branch of science that studies chemicals containing carbon. It explains how living things are made and how materials like medicine and plastic are created.

An inorganic substance is something that does not come from living things, such as plants or animals. In science, it refers to chemicals and minerals like salt, water, and metals that do not contain carbon-hydrogen bonds.