Work and energy Flashcards
What is energy?
it is the property of a system that enables it to do something or make something happen, including the capacity to do work. The SI units for all forms of energy are joules (j).
What is kinetic energy?
the energy associated with the movement of objects. It depends on mass and speed squared (not velocity).
K= 1/2 mv^2
What is potential energy?
energy stored within a system. It exists in gravitational, elastic, electrical, and chemical forms.
What is gravitational potential energy?
related to the mass of an object and its heigh above a zero point, called a datum.
U= mgh
What is elastic potential energy?
related to to the spring constant (a measure of stiffness of a spring.
U= 1/2 kx^2
What is electrical potential energy?
exists between charged particles.
What is chemical potential energy?
is the energy stored in the bond of compounds.
What is total mechanical energy?
the sum of its kinetic and potential energies.
E= U+K
What are conservative forces?
path independent and do not dissipate the mechanical energy of a system. If only the conservative forces are acting on an object, the total mechanical energy is conserved. Examples of conservative forces include gravity and electrostatic forces. Elastic forces, such as those created by springs, are nearly conservative.
What are nonconservative forces?
path dependent and cause dissipation of mechanical energy from a system. While total energy is conserved, some mechanical energy is lost as thermal or chemical energy. Examples include friction, air resistance and viscous drag.
What is work?
a process by which energy is transferred form one system to another. Work may be expressed as the dot product of force and displacement, or the product of force and distance traveled with the cosine of the angle between the two. Work may also be expressed as the area under a pressure-volume curve.
What is power?
power is the rate at which work is done or energy is tranfsferred. The SI unit for power is watt (w).
What is the work-energy theorem?
States that when net work is done on or by a system, the stem’s kinetic energy will change by the same amount. In more general applications, the work done on or by a system can be transferred to other forms of energy as well.
Wnet = ΔK = Kf-Ki
What is mechanical advantage?
it is the factor by which a simple machine multiples the input force to accomplish work. Makes it easier to accomplish a given amount of work because the input force necessary to accomplish the work is reduced. The distance which the reduced input force must be applied, however, is increased by the sam factor (assuming 100% efficiency)
What are the six simple machines?
inclined plane, wedge, wheel and axle, lever, pulley, and screw. Simple machines provide the benefit of mechanical advantage.
= Fout/Fin
