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E260 Lesson 10 (Dong Bing) - Coggle Diagram
E260 Lesson 10
(Dong Bing)
Kinetic energy (KE)
Definition
KE is the energy of an moving objects because of the objects motion. The KE of an moving object depends on the object's mass and its speed
SI Units
KE = Kinetic energy, Joule [J]
Formulae
KE = 1/2 mv^2
Where :
m = mass [kg}
v = velocity [m/s]
KE = Kinetic energy [J]
KE can never be negative so KE >= 0
KE is a Scalar
Gravitational Potential energy (GPE)
Definition
GPE is the energy of an object due to its position above Earth's surface. It is compared to a reference point or base level.
Formulae
GPE = mgh
Where:
m = mass [kg]
g = gravitational acceleration [m/s2] = 9.81 m/s2
h = height [m] (That is above the horizontal zero line)
GPE = gravitational potential energy [J]
SI Units
GPE = Gravitational Potential energy, Joule [J]
Zero line examples
h < 0 = PEg = mgh < 0
h > 0 = PEg = mgh > 0
h = 0 = PEg = mgh = 0
GPE is a Scalar
Elastic potential energy (EPE)
Definition
EPE is energy stored as a result of applying a force to deform an elastic object. Springs and rubber bands store elastic potential energy that can be transformed into kinetic energy. The spring constant k is the amount of force needed to stretch or compress the spring by 1m.
SI Units
EPE = Elastic Potential Energy, Joule [J]
Formulae
EPE = ½ kx2
Where
k = spring constant [N/m]
x = displacement of the spring from neutral position [m]
EPE = elastic potential energy [J]
EPE is a Scalar
Energy
Definition
Energy is the ability to do work or causing a change. When something can change its environment or itself, it has energy
Si Units
Joule [J]
Formulae
Energy [E] = mgh
Energy is a scalar
More Knowleage
Work
Defination
Work is the neergy transferred from a system by a force that act on it and creates an displacement or a change of condition(s)
Work is a Scalar
W = f * D
Frictional force [f]
Other Forms of Energy
Chemical Energy
An energy that is stored in chemical bonds
Examples
Batteries
Natural Gas
bimass
Electrical energy
An energy that is stored in electricity-storing devices
Examples
Capacitor
Electric Batteries
Nuclear Energy
An energy that is stored in particles inside an atomic nucleus.
Examples
Nuclear Fusion
Nuclear Weapons
The Law of Conservation of Energy
Energy cannot be created or destroyed; it may be converted from one form into another, but the total amount of energy never changes
Mechanical energy = potential energy + Kinetic energy
Conservation of Mechanical Energy
PE1 + KE1 = PE2 + KE2
Spring Arrangements
Series
Parallel
Where:
n = number of springs
kn = spring constant for a certain spring
Spring Force
Forumla
Spring Force (Fsp) = - kx
