CLASSICAL MECHANICAL ENERGYKevin Choe

WHAT IS THE MECHANICAL ENERGY?

Gravitational Potential Energy

Kinetic Energy

Total Mechanical Energy Demo Derive equation Problem Solving

POTENTIAL ENERGY

The stored energy of position possessed by an object

Equation PE = mgh

Unit of Potential Energy (kg)(m/s2)(m) = (kg)(m2/s2) = J

KINETIC ENERGY

Energy of motion

Equation KE = 1/2mv2

Unit of Kinetic Energy (kg)(m/s)2 = (kg)(m2/s2) = J

EXAMPLE (FALLING BALL)

GRAPH OF THE EXPERIMENT

TOTAL MECHANICAL ENERGY

What do you see in terms of deriving an equation?

KEi+PEi = KEf+PEf

(1/2mvi2) + (mghi) = (1/2mvf

2) + (mghf)

PROBLEM

What is the speed of the object right before hitting the ground? Derive Vbottom equation from the Total Mechanical

energy. (KEi+PEi = KEf+PEf) Play simple algebra

CALCULATION

KEtop+PEtop = KEbottom+PEbottom

(1/2mvtop2) + (mghtop) = (1/2mvbottom

2) + (mghbottom)

(mghtop) = (1/2mvbottom2)

(ghtop) = (1/2vbottom2)

2ghtop = vbottom2

vbottom = Sqrt(2ghtop)

SOURCE

http://www.physicsclassroom.com http://www.citejournal.org/vol4/iss3/science/

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