energy dissipation and efficiency Flashcards
energy can be either…?
useful or wasted
what happens to wasted energy?
it is dissipated
does friction dissipate energy?
yes, friction always caused energy to be transferred to a thermal store, which is then dissipated into the surroundings.
what is the equation to find the total of the inputted energy?
input energy = useful output energy + wasted output energy
what is the equation for efficiency?
efficiency = useful output / total input
(x100 if you want efficiency as a percentage)
what is the equation for the useful output?
useful output = efficiency x total input
what are sankey diagrams?
sankey diagrams are used to show the useful and wasted output of the total input energy
what does the top arrow on a sankey diagram represent?
the useful output (measured in joules)
what does the bottom arrow on a sankey diagram represent?
the wasted output (measured in joules)
what does the total width of the left side on a sankey diagram represent?
the total energy input (measured in joules)
how do you reduce the energy wasted by friction?
use an oil to lubricate the moving parts to reduce friction
how do you reduce the energy wasted from resistance in a wire?
use a wire with a larger cross-sectional area, and made with a less resistive material
how do you reduce the energy wasted by air resistance?
make the object more aerodynamic
how do you reduce the energy wasted through sound created by machinery?
tighten loose parts in the machine to reduce unnecessary movement
