Physics #2 Flashcards
____ is a system’s ability to do work
energy
what is the unit for kinetic energy?
joule
is kinetic energy related to speed or velocity?
speed. Same kinetic energy regardless of the direction of the velocity vector
potential energy is associated with ______
a given object’s position in space or other intrinsic qualities of the system
can potential energy be negative?
yes, the example with the diver 2 m underwater (sea level is the datum) and his potential energy is now negative.
first law of thermodynamics
conservation of mechanical energy: energy is never created nor destroyed, it is merely transferred from one form to another
____ forces are those that are path independent and do not dissipate energy
conservative
what are the two ways to tell that a force is conservative?
if the change in energy around any round-trip path is zero, or if the change in energy is equal despite taking any path between two points.
when there are no nonconservative forces at play or the work done by nonconservative forces is 0, deltaE = _____
delta U + delta K
change in potential energy + change in kinetic energy
Are nonconservative forces path independent or path dependent?
path dependent
the longer the distance traveled, the larger the amount of energy dissipated.
_____ is not energy but a measure of energy transfer. The other form of energy transfer is _____.
work
heat
what are the ONLY two ways in which energy can be transferred?
work and heat
in fluids, pressure can be thought of as _____
energy-density
when a gas expands, we say that work was done _____ and the work is _____
by the gas and the works
is work done on a system positive or negaitve?
positive
For a given quantity of work, any device that allows for work to be accomplished through a smaller applied force is said to provide _____
mechanical advantage
what are the 6 simple machines that provide mechanical advantage
inclined plane, wedge (two merged incline planes), wheel and axle, lever, pulley, screw (rotating inclined plane)
applying lesser force over a _____ distance provides the same amount of work
greater
In order to move a stationary block without accelerating it on a frictionless surface, how much force needs to be applied?
just equivalent to the objects weight in the direction opposite of where the block will be moved.
how much work will it take to lift something straight up?
force (m x a) x height
increasing the number of pulleys will decrease the effort required to _______, however, the effort must now be applied _____
1/number of pulleys
number of pulleys x load distance
in the work formula, what does the d represent
displacement
in uniform circular motion, the displacement vector and force vector are always ______, so work is ____
perpendicular
0
