Equilibrium, Torque, and Energy

  1. static equilibrium
    zero velocity
  2. dynamic equilibrium
    velocity is not zero
  3. Is equilibrium motionless?

    just, some of all forces acting on the system = 0
  4. straight acceleration (not in equilibrium)

    What is the equation?
    ∑F = ma

    • 1. write equation as if sys. were in equilibrium
    • 2. add "ma" to side with less force
  5. Example: Fdown due to gravity
    Fup due to air resistance
    Fdown > Fup, so

    Fdown = Fup + ma
  6. What does this mean?
    In order to be in equilibrium Fup must be increased by ma
  7. Torque (equation)
    t = F x r x sin
  8. Torque (equilibrium)
    0 net torque
    Tclockwise = Tcounter-clockwise
  9. static equilibrium
    Fup = Fdown
  10. If force is at the point of rotation, what is the torque?
  11. board hanging on a string, in equilibrium
    • F = mass of the board
    • at the center of mass
  12. Units of energy
    • (J) for macroscopic sys
    • (eV) microscopic sys
  13. forms of mechanical energy
    • kinetic energy
    • potential energy
  14. What is kinetic energy?
    What is the equation for kinetic energy?
    energy of motion

    1/2 mv2
Card Set
Equilibrium, Torque, and Energy
Physics Lecture 3