Colin DonnellyMCAT Physics and Math 2.1: Energy
MCAT Physics and Math 2.1: Energy
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Energy refers to a system’s ability to _____ or—more broadly—to _____.
do work
make something happen.
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Different forms of energy have the capacity to perform _____.
different actions.
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Mechanical energy can cause objects to _____.
move or accelerate
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An ice cube sitting on the kitchen counter at room temperature will absorb _____ through heat.
thermal energy
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Kinetic energy is the energy of _____.
motion
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Kinetic energy equation
where K is kinetic energy, m is the mass in kilograms, and v is speed in meters per second.
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The SI unit for kinetic energy, as with all forms of energy, is the _____, which is equal to _____.
joule (J)
kg * m^2 * s^-2
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Kinetic energy is related to _____ and not _____.
speed
velocity
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An object has the same kinetic energy regardless of the direction of its _____.
velocity vector
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Potential energy refers to energy that is associated with a given object’s _____ or other _____.
position in space
intrinsic qualities of the system
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Gravitational potential energy depends on an object’s position with respect to some level identified as the _____.
datum ("ground zero")
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The datum is usually chosen out of _____.
convenience
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Gravitational potential energy equation
U = mgh
...where U is the potential energy, m is the mass in kilograms, g is the acceleration due to gravity, and h is the height of the object above the datum.
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When a spring is stretched or compressed from its equilibrium length, the spring has _____.
elastic potential energy
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Elastic potential energy equation
...where U is the potential energy, k is the spring constant (a measure of the stiffness of the spring), and x is the magnitude of displacement from equilibrium. Note the similarities between this equation and the formula for kinetic energy.
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The sum of an object’s potential and kinetic energies is its _____.
total mechanical energy
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Total mechanical energy equation
E = U + K
...where E is total mechanical energy, U is potential energy, and K is kinetic energy.
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The first law of thermodynamics accounts for the _____, which posits that energy is never _____ — it is merely _____.
conservation of mechanical energy
created nor destroyed
transferred from one form to another
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The total mechanical energy equation _____ obey the first law of thermodynamics.
Why?
does not (necessarily)
there are other forms of energy
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In the absence of nonconservative forces, such as frictional forces, the sum of the kinetic and potential energies will be _____.
constant
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Conservative forces are those that are _____ and that _____.
path independent
do not dissipate energy
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Conservative forces have _____ associated with them.
potential energies
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Perfectly elastic springs have _____, but non-ideal springs produce _____.
conservative energies
friction
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What are two ways to determine if a force is conservative?
pathing between two points (same energy change regardless) and pathing in a circle (net 0 energy change)
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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
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Conservation of mechanical energy in a conservative system
ΔE = ΔU + ΔK = 0
...where ΔE, ΔU, and ΔK are the changes in total mechanical energy, potential energy, and kinetic energy, respectively.
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When nonconservative forces, such as friction, air resistance, or viscous drag (a resistance force created by fluid viscosity) are present, total mechanical energy is _____.
not conserved
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Nonconservative work equation
Wnonconservative = ΔE = ΔU + ΔK
...where Wnonconservative is the work done by the nonconservative forces only.
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Nonconservative forces, unlike conservative forces, are _____.
path dependent
