Energy
- Energy is the ability to do work or the stuff that allows us to make changes
- Energy is conserved so cannot be created or destroyed, only transferred between things
- Stored and transferred not used
- Relative to force and motion
Law of Conservation of Energy
- Energy is conserved so cannot be created or destroyed, only transferred between things
- Energy in a closed system will remain constant
Types of Energy
Kinetic Energy
- K_e or E_k
- Energy stored in the motion of mass
- Measured by the speed/velocity of an object
- U
- Energy based on position
- Potential Energy+Kinetic Energy
- U_g or E_g
- Energy stored in the distance between an object and its source in a gravitation field
- Measured by the amount of distance between objects
- U_s, E_El, or E_s
- Energy stored in the elastic force field
- measured by the amount of compression or stretch
- Effected by the spring constant
- U_int, E_int, E_th, or E_diss
- Energy stored in the random motion on the molecular level or an objects composition
- Measured by the temperature, not heat
- Temp is avg kinetic energy
Energy Transfers
Energy can be transferred from system to system in three ways
- Working (W)
- An external push or pull
- Heating (Q)
- Temperature difference causes energy to transfer from warmer objects ot colder objects to reach an equilibrium
- Radiating (R)
- Matter loses energy by radiating light and gains energy when absorbing light
LOL Chart
LOL charts are used to show the energy change in a system
- The First L is a graph of the initial energy in the system
- The O outlines what is included in the system and any energy transfers in and out of the system
- The second L is a graph of the final energy after the transfers
Work
- Work is the transfer of energy
- Work=Force * Distance
- Joule is the unit of work and energy
- Joule=Nm
- Positive work is energy transferred into the system
- negative work is energy transferred out of the system
- We only care about the components of the force in the direction of the displacement
- Area under a force vs change in X graph is the energy transferred through working
Power
- Power=work/time
- How fast the work is being done
- 1 Joule/second=1 watt
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