Law of Conservation of Energy: the total energy of an isolated system remains constant and can be conserved over time
Mathematical Representation for the Law of Conservation of Energy
∑ᵢ = ∑f
Kᵢ+Pᵢ=Kf+ Pf
mvi²/2+mghf=muf²/2+mghf
SI Units
American Units
The imperial/U.S. units for both energy and work include the foot-pound force (1.3558 J), the British thermal unit (BTU) which has various values in the region of 1055 J, the horsepower-hour (2.6845 MJ), and the gasoline gallon equivalent (about 120 MJ).
In the video it explain work, energy and power. The Law of Conservation of Energy states that energy that the total energy of an isolated system will remain constant and can be conserved over time. This law means that energy can neither be created or destroyed, it can only transform to one form to another. How energy changes depends on the system. Conservative system does not let you lose energy with work.
¹⁾A girl, 30 kg is standing on a 10 meter cliff . She decides to jump off into a water below. How fast is she moving?
²⁾A 1.8 kg book has been dropped from the top of the football stadium. lt's speed is 4.8 m/s when it is 2.9 meters above the ground.
What is its mechanical energy?
KE=½mv² GPE= mgh ME = GPE + KE
½ × 1.8 × 4.8² 1.8 × 10 × 2.9 = 52.2 + 20.7
= 20.75 =52.25 = 74.95
