E&S: Lecture 1

• -scalar quanity, related to the energy content of a system, no direction
• -movement
• -capable of accomplishing work
• -conserved
• -SI system: Joules (J)

• -Act at a distance and cause bodies to accelerate
• -Units: kg m sec^-2
• F =ma

• 1. Gravitational
• 2. Electromagnetic
• 3. Strong nuclear
• 4. Weak nuclear

• -Force integrated over distance
• -lifting things, smashing things takes work
• -Units: Joules (J)
• W=Fd

• -energy associated with moving objects
• KE= 1/2mv^2

• -Massless bundles of electromagnetic energy
• -Electromagnetic radiation cam be described as electromagnetic waves or particles

E=hf

- kinetic energy associated with the random motions of atoms and molecules

Their physical configuration

By doing work againts a conservative force field

Potential energy is relative, not absolute

• other forms of energy
• ex. kinetic energy and heat

Altered by doing work against a gravitational field

Altered by doing work against an elastic material

Altered by doing work against an electrostatic field

Atered by doing work against a magnetic field

Altered by forming and breaking chemical bonds

non-conservative force that resists motion

• -does not store potentiale energy
• -dissipated as heat

• -A scalar quantity related to the rate of energy gain/loss of a system per unit of time
• Unit: Joules/sec=Watts(W)

1.1x10^4 GW

-The change in total internal energy is the sum of heat energy entering the system from its environment plus the work done the system by its environment

• Δ U = Δ Q + Δ W
• Δ U= Internal Energy
• Δ Q= Heat added
• Δ W= Work done

Measure of a system's unvailability to do work on its environment

the lowery its entropy

The higher its entropy

continously increasing

Never decreases

• Only through the application of work
• Ex.Cleaning your room

Increasing entropy

increasing entropy

• 1. In a system, a process that occurs will tend to increase the total entropy of the universe
• 2. Heat generally cannt flow spontaneously from a mateiral at lower temperature. to a material at higher temperature
• 3. It is impossible to convert heat completely into work in a cyclic process