3 - equilibrium, torque, and energy Flashcards
Equilibrium=
static equilibrium=
no translational (straight line) or angular (rotational) acceleration.
if all velocities are at zero.
Dynamic Equilibrium=
all the velocities are constant but not at zero
F upward = F downward
F rightward = F leftward
torque+
a twisting force
(t = Fr sin(theta)
(t = Fl) where l is the level arm
T clockwise = T counter-clockwise
units of energy=
Joule (macroscopic) & electron-volt (eV) (microscopic)
mechanical energy=
is the kinetic energy and potential energy of macroscopic systems.
Kinetic energy (K)=
the energy of motion; any mass moving has this kind of energy
** K = 1/2mv^2**
Potential energy (U)=
is the energy of position. All potential energies are position dependent.
Gravitational potential energy (Ug)=
the energy due to the force of gravity.
Ug = mgh
Elastic potential energy (Ue)=
is the energy due to the resistive force applied by a deformed objet.
** Ue = 1/2k(delta)x^2**
Law of conservation of energy=
states that since the universe is an isolated system, the energy of the universe remains constant. The sum of the all the energy types must remain constant in an isolated system.
Work=
and the three equations:
is the transfer of energy via a force (measured in joules)
- *W = Fdcos(theta)**
* *W = (delta)K + (delta)U + (delta)Ei ** ((no heat))
* *W = (delta)K + (delta)U ** ((no friction, no heat))
Heat=
is the transfer of energy by natural flow from a warmer body to a colder body
**(delta)E = W + q **
—-> most simply way to understand wok is where q is the heat and (delta)E is the total change in the energy of a close system.
Conservative forces=
nonconservative forces=
is conserved in potential energy.
**K1 + U1 = K2 + U2 ** ((conservative forces only, no heat))
the work done is not conserved.
Mechanical energy change:
FkDcos (theta) = (delta)K + (delta)U
3 equations to help solve a work problem:
1) Fdcos(theta)
2) (delta)U
3) everything but (delta)U
