# Fundamental Terms of Physics

## Energy, Work, and Displacement

**Energy** is the ability to do work. **Work** is the energy transferred to an object (force) that causes a displacement. A **displacement** is the measure of the distance moved in a specific direction, or the shortest distance from an initial to a final position. A simple way to think of work is as the amount of energy given to or taken away from an object.

## Joules, Force, and Newtons

Energy and work are most commonly measured in joules ($J$). One **joule** is equal to the energy required for one newton ($N$) of force to perform a displacement of one meter ($m$), or $J=Nm$.

**Force** is energy transferred to an object (a "push" or a "pull") that will change the motion of an object, if unopposed by another force. Force is measured in Newtons. One **newton** is the force required to accelerate one kilogram ($kg$) one meter per second squared, or $1N = \frac{1kg*1m}{1s^2}$. The equation for force can also be written as the product of mass ($M$) and acceleration ($A$), or $F=MA$.

### Video: How Much Energy is One Joule?

## Mass, Velocity, and Acceleration

**Mass** is the amount of matter that makes up an object. Mass is measured in kilograms ($kg$). A **kilogram** was originally defined to equal to the mass of one litre of water, or 1,000 cubic centimeters of water (thus $1g$ is the mass of $1cm^3$ of water). It's still useful to think of kilogram as defined this way; however the formal definition of kilogram is more complicated.

**Velocity** is the distance ($d$) traveled in a given direction over time ($t$), or $V=d/t$ and is often expressed as meters per second ($m/s$).

**Acceleration** is the rate of change in velocity ($V$) over time ($T$), or $A=\Delta{V}/\Delta{T}$, in other words acceleration is how much an object is speeding up, slowing down, or changing direction.

### Video: Acceleration, One-Dimensional Motion

## Kinetic and Potential Energy

**Kinetic energy**is the energy an object possesses by being in motion (moving)**Potential energy**is the energy an object has by being at rest (not moving)

### Gravitational Potential Energy

**Gravitational Potential Energy** is the energy an object has by being at some height and would be converted to kinetic energy when the object is dropped. The force of Gravity on Earth ($G$) is constant at $9.8m/s^2$, therefore to calculate the gravitational energy of an object, we can use $G$ as the value for force, the object's height ($H$) as the distance, and the objects mass ($M$) for the mass, or: $J=MGH$.

## Physics Resources

## Deeper Knowledge on Physics

### Angular Motion

The basics of angular motion

### Electricity

Energy that results from charged particles

### Mechanical Advantage

Learn about mechanical advantage

### Mechanical Engineering

Build and deconstruct mechanical devices

### Power (Physics)

Energy that results from charged particles

### Torque

Learn about torque: Force that causes an object to rotate around an axis.

## Broader Topics Related to Physics

### Science

The most rigorous system of epistemology