Download Kinetic and Potential Energy

Kinetic and Potential Energy
Kinetic Energy
• Kinetic energy is the energy of movement or
motion
• To calculate kinetic energy you need to know
an object’s mass and velocity
• Kinetic energy (KE) = ½ (m)*(v2) = ½ mv2
• Energy is expressed in Joules (J) which are
kg*m2/s2
Example how to calculate kinetic
energy
A 0.10 kg bird is flying at a constant speed of
8.0m/s. What is the bird’s kinetic energy?
Mass (m) = .10kg
Speed (v) = 8.0m/s2
KE = ½ (.10kg)* (8.0m/s)2
KE = 3.2 kg*m2/s2 = 3J
Kinetic Energy Equations
• If you are asked to solve for kinetic energy use
• KE = ½ mv2
• If you are asked to solve for mass use
• M = 2*(KE)/v2
• If you are asked to solve for velocity use
• V = square root 2KE/m
Potential Energy
• Potential energy is the energy stored as a
result of position
• Gravitational potential energy depends on an
object’s height
Formula for calculating potential
energy
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The formula is PEg = mgh = Fgh
Fg will be in Newtons
Where m = mass, g = gravity and h = height
In the second form
F = force in newtons(N), h = height
Gravitational potential energy is expressed in
Joules (J)
Example of calculating gravitational
potential energy
• A diver at the top of a 10.0 m high diving
platform has a mass of 50.0kg. What is her
potential energy?
• PE = mgh
• PE = (50.0kg)*(9.8m/s2)*(10.0m)
• PE = 4900 kg*m2/s2 = 4900J
Potential Energy Equations
• If you are asked to solve for potential energy use
• PE = mgh or PE = Fgh
• If you are asked to solve for mass use
• m = PE/gh or m = PE/Fgh
• If you are asked to solve for height use
• h = PE/mg or use h = PE/Fg
Elastic Potential Energy
• Elastic potential energy is the energy stored in
an object that is stretched or compressed
(think elastic)
• The energy is stored when the object is either
stretched or compressed
Chemical Energy
• Chemical energy is the energy stored in
chemical bonds
• The energy is released when the bonds are
broken
Electric Energy
• Electric energy is the energy associated with
electric charges
• Batteries contain electric energy
Nuclear Energy
• Nuclear energy is the energy stored in the
nucleus of an atom
• Energy can be released by nuclear fission
which is splitting the atom or by nuclear
fusion which is joining nuclei