Physics Chapter 2: Work and Energy
Energy is neither created of destroyed, it is merely transferred from one form to another.
Conservation of Mechanical Energy
Forces that are path independent and do not dissipate energy
Conservative
Total Mechanical Energy formula
E=U+K
Property of a system that enables it to do something or make something happen, including the capacity to do work
Energy
Potential energy formula
U=mgh
The work done on or by a system undergoing a thermodynamic process can be determined by finding the ___________ enclosed by the corresponding pressure-volume curve
area
When the work is done _____ a system, the work is said to be positive. When work is done ___ a system, the work is said to be negative
by, on
The first law of thermodynamics accounts for the ___________________
conservation of mechanical energy
All simple machines are can approximated as ________ systems if we ignore the small amount of energy that is lost due to external forces
conservative
Elastic forces can be approximated to be _______.
conservative
Gravity, electrostatic forces, and elastic forces are examples of _______ forces
conservative
Gravitational and electrostatic forces
conservative forces
The present of nonconservative forces result in mechanical energy not being _____
conserved
In the absence of nonconservative forces such as friction, the sum of the kinetic and potential energies will be _____
constant
Total mechanical energy of a system with conservative forces remains ______.
constant
When the work done by nonconservative forces is zero, or when there are no nonconservative forces acting on the system, the total mechanical energy of the system remains ________
constant
ground/zero potential energy position
datum
As the length of an inclined plane increases, the force required to move an object the same displacement ____
decreases
Total mechanical energy of a system with non conservative forces _________.
decreases
Increasing the number of pulleys ____ the tension in each segment of rope; this leads to an _______ in the mechanical advantage of the setup.
decreases, increases
When a device provides mechanical advantage, it _____ the input force required to generate a particular _____ force
decreases, output
Mechanical advantage is a ratio and is _________ as a result
dimensionless
The work energy theorem offers a ______ relationship between the work done by all the forces acting on an object and the change in ___________ of that object.
direct, kinetic energy
An object has the same kinetic energy regardless of the _________ of its velocity vector, and is related to _____, not ____ as a result.
direction, speed, velocity
Only forces parallel or antiparallel to the _______ vector will do work.
displacement
The path ______ matter in conservative forces and _____ matter in nonconservative forces.
does not, does
Work is a _________, and as a result is the function of the _______ of the angle between the vectors
dot product, cosine
Measure of the amount of useful work generated by the machine for a given amount of work put into the system.
efficiency
Percentage of the work put into the system that becomes unusable due to nonconservative forces or external forces
efficiency
Real pulleys and real machines fail to conform to idealized conditions and therefore do not achieve 100% _______ in conserving energy output to input
efficiency
Related to the spring constant and the degree of stretch or compression of a spring squared
elastic potential energy
U=1/2kx^2
elastic potential energy
When a spring is stretched or compressed from its equilibrium length, the spring has ____________
elastic potential energy
System's ability to do work or make something happen
energy
Pressure can be thought of as an "___________ ___________"
energy density
Work is not energy but a measure of ____________.
energy transfer
If the energy change is ________ regardless of the path taken, then the forces acting on the object are again all conservative
equal
The net work done by forces acting on an object will result in an ___ change in the object's __________.
equal, kinetic energy
Characteristic length where a spring is considered relaxed, or in equilibrium
equilibrium length
Energy is transferred through the process of work when something ____ on or against something else
exerts force
Work can be described as the application of _____ through some _____
force, distance
Energy that depends on an object's position with respect to some level identified as datum
gravitational potential energy
There are two types of potential energy that are dissipated as movement ____ potential energy and _____ potential energy
gravitational, elastic
The height use in the potential energy equation is relative to whatever the problem states is the _______. It will often be simply the distance to the ground, but it doesn't need to be. The zero potential energy position may be a ledge, desktop, or platform.
ground level
Six simple machines
inclined plane, lever, pulley, screw, wedge, wheel and axle
Adding more pulleys further _____ mechanical advantage: for each additional pair of pulleys, we can reduce the effort further still.
increases
As the effort decreases in a pulley system, the effort distance to maintain the same work output _______
increases
There are an ______ number of paths between an initial and final state. Different paths require ____ amounts of work.
initial, different
For processes in which the pressure remains constant, they are termed _____________ and can be calculated by multiplying the ____ by the ______.
isobaric, pressure, volume
When the pressure is constant and no work is done, the process is called _________ or _________.
isovolumetric, isochoric
SI Unit for kinetic energy
joule
SI Unit for work
joule
kgxm^2/s^2
joule
Energy associated with the movement of objects. It depends on mass and speed squared
kinetic energy
Energy of motion
kinetic energy
Objects that have mass and that are moving with some speed will have an associated amount of ___________.
kinetic energy
1/2mv^2
kinetic energy formula
When considering simple machines, ____ and _____ are both forces. The load determines the necessary _____ force . From the output force and mechanical advantage, we can determine the necessary ____ force
load, effort, output, input
The work done by the nonconservative forces will be exactly equal to the amount of energy "_______" from the system.
lost
The work-energy theorem allows us to calculate work without knowing the _______ of forces acting on an object or the _________ through which the forces act.
magnitude, displacement
Gravitational potential energy is directly related to the ______ of the object and it's ______ above a reference point
mass, height
The idealized pulley is ____ and ____ and under these conditions, the work put into the system will exactly equal the work that comes out of the system
massless, frictionless
Conservative forces conserve ______ energy
mechanical
Measure of the increase in force accomplished by using a tool
mechanical advantage
Ratio of magnitudes of the force exerted on an object by a simple machine to the force applied on the simple machin
mechanical advantage
If the displacement occurs over a distance equal to the displacement, then the force required to lift the object will equal ____, but if the distance is greater tan the displacement, then the applied force will be ____ than mg
mg, less
Kinetic energy is the energy of ______
motion
If the volume stays constant as the pressure changes, then _____ work is done.
no
Friction, air resistance, or viscous drag are ___________ forces
nonconservative
Air resistance is a _______ force
nonconservative force
The decrease in work output is due to _________ forces or _________ forces that generate or dissipate energy
nonconservative, external
If the pressure remains constant as the volume changes, then the area under the curve is a rectangle of length _____ and width _____.
p, v
Nonconservative forces, unlike conservative forces are ______________. The longer the distance traveled, the larger the amount of energy dissipated.
path dependent
Potential energy is energy associated with a given _______ or intrinsic property of a system.
position
Energy stored within a system. It exists in gravitational, elastic, electrical, and chemical forms
potential energy
Energy that is associated with a given object's position in space or other intrinsic qualities of the system.
potential energy
U=mgh
potential energy
The sum of an object's ___ and ___ energies is its ______________ energy
potential, kinetic, total mechanical
The rate at which energy is transferred from one system to another
power
Work is the _____ by which energy is ________ from one system to another
process, transferred
If one calculates the change in kinetic energy experienced by an object, then the ______ done on or by an object is the ______
same
For a given quantity of work, any device that allows for work to be accomplished through a _____ applied force is thus said to provide mechanical advantage
smaller
Kinetic energy is related to _____, not ______
speed, velocity
K
spring constant
Measure of the stiffness of a spring
spring constant
If frictional forces are present, some of the mechanical energy will be transformed into _____ and will be _____.
thermal energy, lost
Nonconservative forces dissipate mechanical energy as ______ or ______ energy
thermal, chemical
E=U+K
total mechanical energy
The energy "lost" from a system from the work done by nonconservative forces is _______ into another form of energy
transformed
We say that work had been done when the __________ of the system has changed due to an applied pressure
volume
SI Unit for power
watt
W= FXD
work
Product of effort and effort distance
work input
Product of load and load distance
work output
Sloping inclines, such as hillsides and ramps, make it easier to lift objects because they distribute the required _____ over a larger _____, decreasing the required force
work, distance
The two forms of energy transfer are ______ and ______.
work, heat
Power is found by dividing the _____ by the ______ over which it is done.
work, time
The relationship between work and energy is described by the _________ theorem
work-energy
If the net change in energy is ___ regardless of the path taken to get back to the initial position, then the forces acting on the object are conservative.
zero
If the change in energy around any round-trip path is ___, or if the change in energy is ______ despite taking any path between two points, then the force is conservative.
zero, equal
