Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
23 Cards in this Set
- Front
- Back
|
Equilibrium
|
-no translational or angular acceleration.
-a system is in equilibrium if the translational velocity of its center of mass and angular velocities of all its parts are constant -the net force acting on a system in equilibrium is ZERO. Fupward = Fdownward Frightward = Fleftward |
|
|
Static equilibrium
|
-If all velocities in a system are zero.
|
|
|
Dynamic equilibrium
|
-If any velocities are nonzero, but all velocities are constant.
|
|
|
Systems not in equilibrium
|
-this means that the center of mass is accelerating translationally or its parts are accelerating rotationally.
Steps for facing a problem that is not in equilibrium: 1. write the equations as if the systems are in equilibrium 2. before solving, add 'ma' to the side with less force. |
|
|
Torque
|
-a twisting force, a vector but the MCAT allows us to think of torque as clockwise or counterclockwise.
-When the lever arm is used, equation for torque is: T =Fl F = the force applied l = is where the position vector is form the point of rotation to the point where the force acts at 90 degrees. (lever arm) |
|
|
Lever arm
|
-a position vector that is from the point of rotation to the point where the force acts at 90 degrees.
|
|
|
Units of energy
|
-Joule
-electron volt |
|
|
Mechanical energy
|
-the kinetic energy and potential energy of macroscopic systems.
|
|
|
Kinetic energy (K)
|
-the energy of motion
K = 1/2mv^2 |
|
|
Potential energy (U)
|
-the energy of position
-all potential energies are position dependent. |
|
|
Gravitational potential energy (Ug)
|
-the energy due to force of gravity
Ug =mgh |
|
|
Elastic potential energy Ue
|
-the energy due to the resistive force applied by a deformed object.
Ue = 1/2kdelta(x)^2 k = hooke's law constant for the object x = displacement from the object's relaxed position |
|
|
Law of Conservation of Energy
|
-since the universe is an isolated system, the energy of the universe remains constant
|
|
|
Work
|
-the transfer of energy via force
W = Fdcos(theta) where F = force d = displacement of the system theta = angle between F and d |
|
|
Heat
|
-the transfer of energy by natural flow from a warmer body to a colder body
|
|
|
Frictional forces
|
-an exception to the work equation because frictional forces change internal energy as well as mechanical energy.
|
|
|
Equation describing total energy transfer due to forces and none to heat
|
W = deltaK + deltaU + deltaEi
|
|
|
Equation describing total energy transfer due to forces and none to heat or friction
|
W = deltaK + deltaU
|
|
|
Conservative Force
|
-mechanical energy is conserved within the system
-When a force acts on a system and the system moves from point A to point B and back, the total work done by the force is zero and it is conservative. -the energy change is the same regardless of the path taken. |
|
|
Law of Conservation of Mechanical Energy
|
-States that when only conservative forces are acting, the sum of mechanical energies remains constant.
K1 + U1 = K2 + U2 or 0 = DeltaK + deltaU |
|
|
Nonconservative forces
|
-forces that change mechanical energy of a system when they do work
examples: -friction -pushing and pulling of animals W = delta(K) + delta(U) |
|
|
Kinetic frictional forces
|
-increase the internal energy of the systems to which they are applied
-does negative work on a sliding box FkD = delta(K) + delta(U) |
|
|
Power
|
-Rate of energy transfer
-unit of power is the Watt (W) which is equivalent to J/s. P = delta(E)/t equation for instantaneous power due to a force: P=Fvcos(theta) |
