# Environmental Science 101Physics

### Physics: An Overview

The science that studies matter and its motion and behavior through space and time; And that studies the related entities of energy and force.

Law I:
Law II:
Law III:

### Force

That which tends to put a stationary body in motion, or to change the direction or speed of a moving body.

### Gravity

The curvature of spacetime caused by the uneven distribution of mass. (Einstein)
A force which causes any two bodies to be attracted to each other, with the force proportional to the product of their masses and inversely proportional to the square of the distance between them. (Newton)

### Stress and Strain

Stress: any force which acts to deform a body
Compression: a stress that acts to press or squeeze bodies together.
Tension: a stress that acts to stretch a body, or pull a body apart.
Shear: stress which acts tangential to a plane through a body, causing two contiguous parts to slide past each other.
Strain: change in shape or volume of a body as a result of stress; deformation.

### Energy

Capacity to do work.
Common forms of energy include:
Kinetic Energy:
Potential Energy:

### Temperature - Heat

Temperature is a measure of heat
Everything has some measure of heat
Amount of heat in an object is related to how fast atoms are moving in that object

### Thermodynamics

Study of behavior of heat and heat transfer.
0th Law: If two systems are both in thermal equilibrium with a third system then they are in thermal equilibrium with each other.
1st Law: The increase in internal energy of a closed system is equal to total of the energy added to the system. Energy can be neither created nor destroyed. However, energy can change forms, and energy can flow from one place to another.
2nd Law: the tendency of natural processes to lead towards spatial homogeneity of matter and energy, and especially of temperature. Thermal energy flows from areas of higher energy to areas of lower energy
3rd Law: At zero absolute temperature the system must be in a state with the minimum thermal energy.

### Waves

The transport of energy and momentum without the transport of matter.
Waves in a gas.
Waves in a fluid.
Waves in a solid.

### Optics

The science of light and how it behaves.

### Nuclear Physics

The field that studies atomic nuclei and their constituents and interactions.

### Electromagnetism

Fundamental force exerted by one particle on another because of electrical charges of the particles.
Electricity: the presence and motion of electric charge (movement of electrons from atom to atom)
Magnetism: an attractive/repulsive force due to a magnetic field

### Special Relativity

Physical theory regarding the relationship between space and time.
1. The laws of physics are invariant (i.e., identical) in all inertial systems (i.e., non-accelerating frames of reference).
2. The speed of light in a vacuum is the same for all observers, regardless of the motion of the light source.
3. The two postulates of special relativity predict the equivalence of mass and energy, as expressed in the mass–energy equivalence formula: E = mc 2