Work and Energy Flashcards
energy
referes to a system’s ability to do work
kinetic energy
objects that have mass and are moving
kinetic energy formula
K=(1/2)mv^2
Joule
measurement of energy; kg*m/s^2
potential energy
energy associated with a given object’s position in space; has the potential to do work
gravitational potential energy
depends on an object’s position with respect to some level identified as the datum (ground, or 0 PE)
gravitational potential energy equation
U=mgh
elastic potential energy
U=1/2kx^2, where x is the magnitude of displacement from equilibrium and k is the spring constant
total mechanical energy
sum of an object’s U and KE; E=U+K
first law of thermodynamics
conservation of mechanical energy; energy is never created nor destroyed
conservative forces
path independent and do not dissipate energy; i.e. gravitational and electrostatic; all energy is conserved
nonconservative forces
friction, air resistance, viscous drag; total mechanical energy is not conserved
work
process by which energy is transferred from one system to another
Work equation
W=Fdcos(theta)
P-V graphs
shoe the work done on or by a system undergoing a thermodynamic process
isovolumetric (isochoric) process
volume stays the same and no work is done
isobaric process
volume changes, pressure stays the same; W=P(delta)V
P-V graph calculation
calculate area of all regions then add together to find work
Power
rate at which energy is transferred from one system to another P=ΔE/t
Watt (W)
Joules/sec
work-energy theorem
Wnet=ΔK=Kf-Ki
simple machines
inclined plane, wedge, wheel and axle, lever, pulley and screw
mechanical advantage
ratio of the force exerted on an object by a simple machine (Fout) to the force actually applied on the simple machine (Fin) (Fout/Fin)
load distance v effort distance
in order to lift an object a certain load distance, the length of rope must be twice that distance
efficiency of a simple machine
Wout/Win aka loadload distance/efforteffort distance
