Work,force,Energy & Efficiency Flashcards
What is Newton’s law of motion?
objects at rest will stay at rest, objects in motion will remain in motion unless acted upon by an outside force
What is the formula for force?
F = ma
m=mass
a=acceleration
what is an unbalanced force?
a force that is not in magnitude, therefore an object will move
what is a balanced force?
a force that is equal in magnitude and in opposite directions so they will cancel each other out
What is work?
when a force moves an object through a distance
what is the formula for work?
W=Fd
W= measured in Joules (J)
F=force, measured in Newtons (N)
d=distance, measured in meters (m)
True or False:
work done to an object equals the energy output or work output
True!
True or False: work input = work output
true!
what is energy? what is the formula?
-the ability to do work
-measured in Joules (J)
E = W
What are the two laws for thermodynamics?
- -energy is never created or destroyed
-the total energy in a system and its surroundings stays constant - -during energy conversions some useful energy is lost as thermal energy
-heat flows from matter at a higher energy level to a lower energy level
what is the idea of the perfect machine? (perpetual motion machine)
-hypothetical
-a machine in which all the input energy is converted entirely into useful mechanical energy
what are the three types of systems?
- Open, can exchange mass and energy
- Closed, can transfer energy but not mass
- Isolated, can’t exchange mass or energy
What is efficiency?
the amount of useful work/energy obtained from an energy conversion divided by the total amount of energy out into the process
what is the formula for efficiency? what are the variations?
% Efficiency =
useful energy output x 100
total energy input
% = UEO
100 = TEI
useful energy output = UEO
total energy input = TEI
True or false: output is always greater than input
False! output is never greater than input bc energy is always lost
