1. Electricity
   Energy
2. The speed of light
   Electrons

While the E stands for the amount of energy that is released, the m stands for mass, and the c stands for the speed of light. This is Albert Einstein's Theory of Special Relativity.

1. The distance something travels over a unit of time
   The amount of pressure put on something
2. The amount of gravitational pull on the specific planet
   The energy produced by something in motion

Speed is often considered the distance that something travels over a period or unit of time. Keep in mind that distance can be how far someone falls to how far someone runs. While time can be measured in various ways including seconds and minutes.

1. Time
   Brightness
2. Distance
   Speed

A light-year is the distance light can travel through space without interruption in a single year. By comparison, if an object were traveling at the speed of light, it would take it one year to reach the distance of a light-year.

1. A conductor
   A high-frequency knob
2. An insulator
   A fountain

Electricity flows through conductors. However, wood doesn't allow electricity to flow through it, so it is considered an insulator. If the wood is wet, electricity can flow through the water, but not the wood itself.

1. Folic numbers
   Particle numbers
2. Partial numbers
   Quantum numbers

Quantum numbers can be used for a variety of things. They generally help determine an electron configuration within an atom, and they help estimate the location of those electrons within an atom.

1. Outside of the magnetic field
   In a paper bag
2. With other paperclips
   Within the magnetic field

The magnetic field of an object is the space around the magnet that attracts other magnetic objects. Stronger magnets have wider magnetic fields, and can attract objects of varying magnetic degrees.

1. A body at rest will stay at rest until acted upon
   Every body is capable of motion
2. Cellular motion doesn't exist
   A planet has an elliptical orbit around a sun

The idea of the first law of motion is that as long as something is not disturbed, it will either continue in uniform motion or at rest. Keep in mind that resistance from air or other objects is considered an external force that acts upon the object in question.

1. Pressurized cells
   Heat radiation
2. Gravity
   Buoyant force

Buoyant force is the upward force on an object that is immersed in any fluid. If the object is lighter than the fluid, it will move upward. An object as light as a beach ball has a lot of buoyant force compared to the water in your pool.

1. Helium
   Nothing can create energy.
2. Oxygen
   Nitrogen

According to the Law of Conservation of Energy, energy itself cannot be created or destroyed. It can only be transferred from one form to another. This means that you can't simply synthesize energy in a lab.

1. Rectilinear motion
   Circular motion
2. Centripetal motion
   Quad motion

Rectilinear motion simply refers to something moving in a straight line. It isn't being affected or interrupted by any other objects or forces. Denser objects are more likely to move rectilinearly, because they are less affected by lower forces.

1. Photons
   Nucleons
2. Electrons
   Neurons

Nucleons can be used as a term that represents either protons or neutrons within the nucleus of an atom. The total number of nucleons in an atom determines the mass number of the isotope.

1. The number of electrons the atom has
   The number of neurons in a single cell
2. The number of atomic pounds it weighs.
   The number of protons in a single atom's nucleus.

Each element on the periodic table has a specific number assigned to it. These numbers represent the amount of protons a single atom of that element has in the nucleus. This number often affects the atomic weight of the atom.

1. Refraction
   Reflection
2. Renuncian
   Reunion

Reflection doesn't just occur with light or things that you see. Sound waves can also reflect. The most perfect example of this is an echo. When a wave of any sort bounces off a boundary, it is reflecting.

1. The amount of water vapor in a sample of air compared to the entire volume of the sample
   The amount of air in a water sample
2. The amount of water in a standard sample
   The amount of standing water in an air sample as compared to water in ten other samples.

Humidity is the amount of water in the air. To find absolute humidity, you have to take an air sample, and find out how much water vapor is in it. Once you know how much water vapor is in the sample, you can compare it the size of the sample. The resulting ratio is considered absolute humidity.

1. Distance
   Time
2. Temperature
   Pressure

Pascals are units of pressure that are equal to one Newton acting consistently (uniformly) over a 1m^2 area. They are normally used to measure the internal pressure or stress on something.

1. Motion that is unstable
   Motion that happens in regular intervals
2. Motion that occurs when no force is exerted
   There is no such thing as periodic motion.

Though the intervals in any given periodic motion might be different, the definition is the same. Even if we only see something happen once a year, it is still considered periodic motion, because it can be predicted.

1. Law of gravity
   Law of motion
2. Law of physical astronomy
   Law of planetary motion

There are three laws of planetary motion, and they dig deep into how plants move around the sun. One of them even states that, "The square of the period of a planet is directly proportional to the cube of the radius of the semi-major axis of the orbit."

1. Rubbery
   Supple
2. Modulusly
   Elastically

Elasticity in an object is important for all things physics. If you've ever had to create a contraption that allows you to drop an egg off a balcony without it cracking, you did a lot of experimentation with elasticity of various materials.

1. Swayback
   Trap light
2. Oscillatory motion
   Gravity

Oscillatory motion can only happen if the object in motion has an equilibrium or a mean position. This is the position the object would stand at rest at. When you think of a pendulum, you see that it sways, but doesn't bounce. This is because of the oscillatory motion.

1. Absolute boil
   Absolute zero
2. 174 degrees F
   25 degrees F

Absolute zero is the temperature at which all motion ceases and vanishes, and nothing can move, including ions. The temperature is -273.16 degrees F or -273.15 degrees C. This theoretical temperature is 0 on the Kelvin scale.

1. Vapor
   Liquid
2. Solid
   Jelly

While amorphous substances can be jelly-like, jelly is considered a solid. The term amorphous refers to the fact that this substance does not have a clear shape or form that can be defined.

1. Laser
   Flashlight
2. Telescope
   Gravitational spot light

While lasers were all the rage in movies in the 1980s and '90s, they served an even greater purpose in the field of physics. They help scientists from all branches conduct experiments with distance and light.

1. How hard I hit the ball
   The nucleus of the ball
2. The person throwing the ball
   Whether or not the sun is out

According to the second law of motion, the rate of change is always directly proportional to the amount of force that was applied. Depending on how hard you hit the ball, the directional change will coincide with it.

1. There is no difference.
   Heat only exists over 80 degrees F.
2. Temperature is internal while heat is transferred.
   Temperature can be measured, heat cannot.

In the world of physics, it's important to know the difference between heat and temperature. The temperature is a measurement of the internal energy in a system, element or body. On the other hand, heat is the measurement of energy that is transferred from one thing to another.

1. 4,184
   14.245
2. .1458
   2,147

Few realize that a calorie is actually a unit of heat. One calorie is equal to 4,184 joules. This is the energy that is required to raise the temperature of 1 gram of water by 1 degree C.

1. Alpha particles
   Gamma rays
2. Gamma particles
   Beta rays

Radioactive decay causes a lot of different types of radiation and the release of several different types of particles. Gamma rays create penetrating electromagnetic radiation from the decay of atomic nuclei.

1. Atoms that have the same number of neutrons but a different number of protons
   Atoms that are missing protons
2. Atoms that have electrons, protons and neutrons in the nucleus
   Atoms that have the same number of protons but a different number of neutrons

When atoms of the same element have different mass, it is because they have different number of neutrons. However, all of the atoms will have the same number of protons in isotopes.

1. Blast
   Joule
2. Calorie
   BTU

There are many different ways to measure heat. In most sciences, the measurement for heat is in joules. However, heat can also be measured in calories and BTUs (which stands for British Thermal Units) in the metric system.

1. Kelvin
   Kinetic energy
2. Thermoscience
   Free falling

Kinetic energy is how much energy a body has based on its motion. In the equation K=1/2mv^2, the m represents the mass of the body (or object) and v represents the speed at which it is going.

1. Aristotle
   Galileo
2. Kepler
   Heisenberg

As early as 1609, Johannes Kepler started creating the laws of planetary motion. Based on his observations, he ended up with three laws of planetary motion by 1619. These laws are still used to study the stars today.

1. Adding the number of protons and electrons in a nucleus
   Adding the number of protons, neutrons and electrons in a nucleus
2. Adding the number of protons and neutrons in a nucleus
   Adding the number of neutrons and electrons in a nucleus

It is important to remember that the mass number of an element is different from the atomic number. In order to find the mass number, you have to add the number of protons and neutrons.

1. Pascal's Law
   Newton's Law of Gravity
2. The Second Law of Planetary Motion
   The First Law of Motion

Pascal's law is essential for fluid mechanics and hydraulics. This law states that any pressure put on a fluid will be dispersed equally across the fluid. This is because fluid is able to move and adjust to the pressure.

1. Gamma particle
   Beta particle
2. Alpha radiation
   Omega divide

Beta particles move very fast, and they are always emitted by the radioactive decay of a substance. This emission of particles was once called a ray, and these particles are also known as beta radiation.

1. Refracted light
   Stream light
2. Polarized light
   Retracted light

Polarized light is when light waves vibrate on the same plane, while unpolarized light is when they are vibrating on different planes. You can transform unpolarized light into polarized light through polarization.

1. The speed of the sound
   The amount of light in the room
2. The shape of the boundary
   Sound doesn't reflect.

There are a few things that affect how sound reflects off surfaces (also known as boundaries). Sound waves can reflect at angles, much like light, and the sound can be distorted as well.

1. Reflection
   Daining effect
2. Marking
   Refraction

Refraction is the bending of light when it is passed through something. This bending of light is sometimes visible to the naked eye, in that it creates a rainbow effect, as the different colors bend.

1. Restoring force
   Restarting force
2. Swing force
   Sitting force

Restoring force is the force that works to bring oscillating objects (like a pendulum or swing) back to its mean position, or resting position. This is the position that the swing is in naturally, and when there aren't outside factors, it can rest rather quickly.

1. A frigid body
   A rigid body
2. A malleable body
   A microbody

Rigid bodies tend to have a fixed size and shape. Outside forces do not change the structure of the body when applied. The ability to remain unaltered allows scientists to study it better.

1. Flushed air
   Condensed air
2. Saturated air
   Hot air

Saturated air is air that allows evaporation and condensation to exist in equilibrium. This happens when two unsaturated air masses mix or the air cools. It often happens in the atmosphere.

1. When something is traveling 100 miles per hour
   When something is traveling slower than 10 miles per hour
2. There is no such thing as a sonic boom.
   When something is traveling faster than the speed of sound

Sonic booms occur when pressure waves stack on top of each other and create a shock wave. This usually only happens if the source of the sound is traveling at or over the speed of sound itself.