Chapter 2: Work and Energy Flashcards
(26 cards)
____________ refers to a system’s ability to do work or - more broadly - to make something happen.
Energy
________________ is the energy of motion. Objects that have mass and that are moving with some speed will have an associated amount of ________________.
Kinetic energy
______________ refers to energy that is associated with a given object’s position in space or other intrinsic qualities of the system.
Potential energy
___________________ depends on an object’s position with respect to some level identified as the datum (“ground” or the zero potential energy position).
Gravitational potential energy
When a spring is stretched or compressed from its equilibrium length, the spring has __________________.
Elastic potential energy
The sum of all object’s potential and kinetic energies is its __________________.
Total mechanical energy
The first law of thermodynamics accounts for the _____________________, which posits that energy is never created nor destroyed - it is merely transferred from one form to another.
Conservation of mechanical energy
_______________ forces are those that are path independent and that do not dissipate energy.
Conservative forces
If the change in energy around any round-trip path is zero - of if the change in energy is equal despite taking any path between 2 points - then the force is _______________.
Conservative
_______________ forces (such as gravity and electrostatic forces) conserve mechanical energy.
Conservative forces
_______________ forces (such as friction and air resistance) dissipate mechanical energy as thermal or chemical energy.
Nonconservative forces
When _________________, such as friction, air resistance, or viscous drag (a resistance force created by fluid viscosity) are present, total mechanical energy is not conserved.
Nonconservative forces
_________ is not actually a form of energy itself, but a process by which energy is transferred from one system to another.
Work
_________ is not energy but a measure of energy transfer. The other form of energy transfer is heat.
Work
The work done on or by a system undergoing a thermodynamic process can be determined by finding the area enclosed by the corresponding ____________________ curve.
Pressure-volume curve
If volume stays constant as pressure changes, then no work is done because there is no area to calculate. This is called an _______________ or _____________ process.
- Isovolumetric
- Isochoric process
If pressure remains constant as volume changes, then the area under the curve is a rectangle of length P and width change in V. The processes in which pressure remains constant are called _______________.
Isobaric processes
___________ refers to the rate at which energy is transferred from one system to another.
Power
The __________________ offers a direct relationship between the work done by all the forces acting on an object and the change in kinetic energy of that object.
Work-energy theorem
For a given quantity of work, any device that allows for work to be accomplished through a smaller applied force is thus said to provide __________________.
Mechanical advantage
_________________ is the ratio of magnitudes of the force exerted on an object by a simple machine (F out) to the force actually applied on the simple machine (F in).
Mechanical advantage
Assuming that the crate is momentarily being held stationary in midair, we again have a system in translational equilibrium: the weight (the ________) is balanced by the total tension in the ropes.
Load
Assuming that the crate is momentarily being held stationary in midair, we again have a system in translational equilibrium: only half the force (_________) is required to lift the crate as each rope supports one-half of the crate’s total weight.
Effort
In the pulley model, to lift an object to a certain height in the air (the _______________), one must pull through a length of rope (the _______________) equal to twice that displacement.
- Load distance
- Effort distance
