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Lesson 08: Mechanical Energy - Coggle Diagram
Lesson 08: Mechanical Energy
a. Definition
Definition of Energy & Work
Work is the energy transferred to or from a system by a force
Energy and Work are both ‘Scalar’ and not ‘Vector’
Energy is the ability to do work or to cause change
Energy
Potential Energy
Gravitational Potential Energy
is the energy of an object due to its position above Earth’s surface
Elastic Potential Energy
is energy stored as a result of applying a force to deform an elastic object
is stored in the object
Kinetic Energy
is the energy of a moving object because of its motion, which depends on the object’s mass and its speed
Spring Force
is the force produced by the free end of the spring and is not constant as an object is pushed or pulled
In series, springs have same force passing through them, as each contributes to the total deflection
In parallel, springs have same deflection, and total force is split among them.
b. SI Units
Joule (J) for Energy (Kinetic, Gravitational Potential & Elastic Potential)
Kilogram (kg) for Mass
Metre per Second (m/s) for Velocity
Metre per Second Square (m/s2) for Gravitational Acceleration
Metre (m) for Height
Newton/Metre (N/m) for Spring Constant
Metre (m) for Displacement from Neutral Position
Newton (N) for Force (Spring Force)
c. Formulae
Kinetic Energy
KE = ½ mv2
Gravitational Potential Energy
GPE = mgh
Elastic Potential Energy
EPE = ½ kx2
Spring Force
Spring Force (Fsp) = - kx
Other Forms of Energy
Chemical Potential Energy
Electrical Energy
Nuclear Energy
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
Total Energy in the beginning = Total Energy in the end
PE1 + KE1 = PE2 + KE2
