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- Define a system in equilibrium
- The net force in a system is equal to zero.
- This means there is no acceleration
How to solve equilibrium problems
- Put opposing forces equal to each other.
- In not in equilibrium, add ma to weaker side
Define torque and give equations
- Torque: rotational force
What are the units of Energy
- Joule (J): in macroscopic world 1
- Electron-volt (eV): in microscopic wold
Name mechanical energies and give equations
- Kinetic: (1/2)mv^2
- Gravitational potential: mgh
- Elastic potential: (1/2)kΔx^2
How is energy transfered
Heat or work
Give equations for work and how do you know if work is being done
- W=fdcos(theta) when no friction is present
- W=ΔK+ΔU+ΔE(friction) no heat
- 1: define a system
- 2: does heat of system or surrounding change. If there. Is no heat, all energy is transfered into work
What are the conservative forces, and how do you tell if a force is conservative or not?
- 1: gravity
- 2: Hooke's law forces
- 3: electromagnetic
- No displacement occurs (loop) and ΔE is the same regardless of the path taken. Force is dependent on position
How are non-conservative forces different from conservative ones? What is the equation?
- Mechanical energy will change when work is done. Energy change is not stored as potential energy
Define power and give the equation and units
- Power: rate of energy transfer or work done on system (E changes when work is done ΔE=W+h
- Watt: J/sec
- P=ΔE/time or ΔW/time
- Instantaneous power=Fvcos(theta)