Conservation of Energy
- In the previous section, we have introduced different types of energy, such as kinetic energy, gravitational potential energy, spring potential energy, and thermal energy. An important theory that combines different forms of energy together is called the conservation of energy.
The above figure shows one way of expression the conservation of energy. Another way (this is also a quicker way) to see the equation of that energy gained is equal to energy lost. If the total energy of a system remains unchanged, and it gains energy in other during a process, then it must lose the equal amount of energy.
Application of Conservation of Energy
- Gravity light is an invention that produces light by using the theory of conservation of energy without expensive economic costs, helping communities in Africa with no access to lights.
Test Yourself
A Challenging Question
A string with a length of 0.8 meters hangs a board from a celling. A newly invented weapon shoots a bullet at an initial velocity of 120m/s that collides with a piece of wood of 1.5kg. After the collision, the woods start to oscillate, and the bullet leaves with a velocity of 100m/s. Calculate the maximum angle between the string and its initial position with the board.
