Energy and Equilibrium Flashcards
torque
is a measure of a force’s ability to cause rotational acceleration
if a net force acts on an objects center of mass
the object accelerates translationally
If a net force acts on any other spot than the center of mass
the objects accelerates rotationally
is torque a vector or scalar
vector
lever arm
where one side has a force acting at 90degrees and the other at some other force making sin 90=1
the greater the net torque on an object the greater
its acceleration
torque increases as
the component of the force acting perpendicular to the position vector increases
as the distance between the point of application of the force and the point of rotation increase
a system is in equilibrium if
the translational velocity of its center of mass and the angular velocities of all its parts are constant
if all velocities acting on the object are zero
static equilibrium
if any velocities are nonzero but all the velocities are constant
dynamic equilibrium
terminal velocity for a skydiver
when the gravitational downward force is equal to the force of air resistance upward
isolated system
cannot exchange mass or work and heat
open system
can exchange work, heat, and mass with the surroundings
closed system
can exchange work and heat with the surroundings but cannot exchange mass
joule units
1kgm^2/s^2
mechanical energy vs non-mechanical energy
mechanical energy is energy on the macroscopic level while non-mechanical energy is energy on the microscopic level
gravitational potential energy
is the energy created by the force of gravity
heat
is energy that is transferred between a system and its surroundings due to a temperature difference between them
work
is energy transferred for any reason other than a temperature difference. Is scalar and is measured in units of energy (joules)
First law of thermodynamics equation accounting for energy
W+q = change in energy
Energy total equals the sum of all forms of energy in that system
change in energy total= Emechanical+Einternal
Equation for energy ignoring internal energy because internal energy is measured by friction
W+q=change in K +change in U
Work-kinetic energy theorem
W= change in kinetic energy
work done by a system
negative value for work
work done on a system
positive value for work
power equations
rate of energy transfer P=w/t P=E/t (E=energy change of the system which equals work plus heat)
power unit
watt (J/s)
conservative forces result in
zero change in energy in the system
does a conservative force do work
no because there is not any work lost or gained in the system
non-conservative forces equals the
change in mechanical energy of the systems upon which they are applied W=change in K+change in U
for energy equations
if there is a heat or pressure-volume change then it is a thermodynamic problem. If not then it is a transfer of work
