force A force is a push or pull upon an object resulting from the object's interaction with another object. pull A pull is a force that acts in the direction of the origin of the force.

motion Motion (physics), any physical movement or change in position or place. gravity Gravity is the force that causes two particles to pull towards each other.

position speed The point or area occupied by a physical object Speed is the rate of motion, or equivalently the rate of change in position, often expressed as distance traveled per unit of time.

direction The line or course on which something is moving or is aimed to move or along which something is pointing or facing. mass

lever simple machines wedge lever pulley screw inclined plane A lever is a simple machine that makes work easier for use; it involves moving a load around a pivot using a force. simple machines wedge lever pulley screw A simple device, such as a lever, pulley, or inclined plane; a machine without moving parts. inclined plane wheel and axle

inclined plane pulley

wedge screw

Wheel and axle

Light transparent Allowing light to pass through A range of electromagnetic radiation that can be detected by the human eye transparent Allowing light to pass through

translucent opaque Allowing only some light to pass through Not allowing light to pass through

Reflection Refraction The bouncing of light off an object The bending of light as it moves from one material to another

Convex lens Concave lens A lens that is thicker at the center than it is at the edges Concave lens A lens that is thicker at the edges than it is at the center

prism A triangular piece of cut glass used to break white light up into its constituent colors. ROY G. BIV The color seen in a rainbow: red, orange, yellow, green, blue, indigo, and violet.

spectrum The different colors of light that are coming from a star Color The byproduct of the spectrum of light as it is reflected or absorbed

rainbow An arc of colored light in the sky caused by refraction of the sun’s rays by rain vibration A quick back-and-forth motion; a trembling motion

Sound wave pitch How high or low a sound is Waves formed by compression of the material (as air) through which they travel regardless of whether they can be heard. pitch How high or low a sound is

Loud Soft Not loud, harsh or irritating Marked by intensity or volume of sound Soft Not loud, harsh or irritating