# Law of Conservation of Energy

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Law of conservation of energy, also called conservation of energy, states that energy cannot be created or destroyed, but may be changed from one form to another.  This means that the total energy in an isolated system remains constant over time.

## law of conservation of Energy formulas

 $$\large{ \frac{1}{2}\; m_f \; v_f^2 + m_f \; g_f \; h_f^2 = \frac{1}{2}\; m_i \; v_i^2 + m_i \; g_i \; h_i^2 }$$ $$\large{ KE_f + PE_f = KE_i + PE_i }$$

### Where:

 Units English Metric $$\large{ g }$$ = gravity $$\large{\frac{ft}{sec^2}}$$ $$\large{\frac{m}{s^2}}$$ $$\large{ h }$$ = height $$\large{ft}$$ $$\large{m}$$ $$\large{ m }$$ = mass $$\large{lbm}$$ $$\large{kg}$$ $$\large{ v }$$ = velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$\large{ KE }$$ = kinetic energy $$\large{ bf-ft }$$ $$\large{J}$$ $$\large{ PE }$$ = potential energy $$\large{ lbf-ft }$$ $$\large{J}$$ $$\large{ f }$$ = final - - $$\large{ i }$$ = initial - -