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 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