Motion, Forces, Energy, Waves, and Optics Concepts
Motion: Change in Position
Motion is the change in position of an object relative to a reference point.
Frame of Reference
A frame of reference is a system for specifying the precise location of objects in space and time.
Displacement
Displacement is the change in position of an object. It always includes direction.
Speed
Speed is the distance traveled divided by the time interval during which the motion occurred.
Velocity
Velocity is the speed of an object in a particular direction.
Acceleration
Acceleration is the rate at which velocity changes.
Force
Force is any action that can change the state of motion of an object.
Friction
Friction is an unbalanced force that acts against the direction of motion.
Static Friction
Static friction is the force that resists the initiation of sliding motion between two surfaces that are in contact and at rest.
Kinetic Friction
Kinetic friction is the force that opposes the movement of two surfaces that are in contact and are moving over each other.
Inertia
Inertia is the tendency of an object to resist a change in motion unless an outside force acts on the object.
Weight
Weight is a measure of the gravitational force exerted on an object.
Free Fall
Free fall is the motion of a body when only the force of gravity is acting on it.
Terminal Velocity
Terminal velocity is the constant velocity of a falling object when the force of air resistance is equal in magnitude to the force of gravity.
Projectile Motion
Projectile motion is the curved path that an object follows when thrown, launched, or otherwise projected near the surface of Earth.
Momentum
Momentum is a quantity defined as the product of the mass and velocity of an object.
Work
Work is the transfer of energy to an object by the application of a force that causes the object to move in the direction of the force.
Power
Power is a quantity that measures the rate at which work is done or energy is transformed.
Mechanical Advantage
Mechanical advantage is a quantity that expresses how much a machine multiplies force or distance.
Simple Machines
Simple machines are one of the six basic types of machines, which are the basis for all other forms of machines.
Compound Machines
Compound machines are machines made of more than one simple machine.
Energy
Energy is the capacity to do work.
Potential Energy
Potential energy is the energy that an object has because of its position, shape, or condition.
Kinetic Energy
Kinetic energy is the energy of an object due to the object’s motion.
Mechanical Energy
Mechanical energy is the amount of work an object can do because of the object’s kinetic and potential energies.
Efficiency
Efficiency is a quantity, usually expressed as a percentage, that measures the ratio of useful work output to work input.
Sound and Light Waves
Sound Waves
Sound waves are longitudinal waves caused by vibrations and travel through a material medium.
Pitch
Pitch is a measure of how high or low a sound is perceived to be, depending on the frequency of the sound wave.
Infrasound
Infrasound refers to slow vibrations of frequencies lower than 20 Hz.
Ultrasound
Ultrasound refers to any sound wave with frequencies higher than 20,000 Hz.
Resonance
Resonance is a phenomenon that occurs when two objects naturally vibrate at the same frequency.
Sonar
Sonar is a system that uses acoustic signals and echoes to determine the location of objects or to communicate.
Photons
A photon is a unit or quantum of light.
Intensity
Intensity is the rate at which energy flows through a given area of space.
Radar
Radar is a system that uses reflected radio waves to determine the velocity and location of objects.
Light Rays
A light ray is a line in space that matches the direction of the flow of radiant energy.
Virtual Image
A virtual image is an image from which light rays appear to diverge; it cannot be projected on a screen.
Real Image
A real image is an image formed by the intersection of light rays; it can be projected on a screen.
Lens
A lens refracts light waves such that they converge or diverge to create an image.
Magnification
Magnification is the increase of an object’s apparent size by using lenses or mirrors.
Prism
A prism is a system that consists of two or more plane surfaces of a transparent solid at an angle with each other.
Dispersion
Dispersion is the process of separating a wave of different frequencies into its individual component waves.