The Law of Conservation of Energy in Real Life | POINT classical mechanics
There are many examples of the mutual transformation between potential energy (PE) and kinetic energy (KE), including:
(1) Throwing an object (a ball) upwards
(2) A high-flying spiral in track and field
(3) Shooting an arrow from a bow
(4) A roller coaster
(5) Still water behind a dam
(1) Throwing an object (a ball) upwards:
- When a ball is thrown vertically upwards from a certain level, its potential energy is zero and its kinetic energy is maximum.
- When the ball begins to move upward, its potential energy gradually increases and its kinetic energy decreases by the same amount. This continues until the ball reaches its maximum height, at which point the kinetic energy is zero and the potential energy is maximum.
- When the ball begins to return to the level from which it was thrown, its kinetic energy increases and its potential energy gradually decreases until it reaches the level from which it was thrown again, at which point the potential energy is zero and the kinetic energy is maximum
(2) High jump in athletics:
- Potential energy is stored in the pole during the jump and converted into kinetic energy.
(3) Shooting an arrow from a bow:
- Potential energy is stored in a taut string and converted into kinetic energy when released.
(4) A roller coaster:
- Amusement park carts use a huge engine to pull the cars to the top of the rise, storing a large amount of potential energy because the engine used energy against gravity to lift the cars and the people inside. When the train cars reach the top of the curve and drop back down, the potential energy is gradually converted into kinetic energy. Neglecting frictional forces, the sum of the two energies remains constant. Therefore, the first rise must be the highest to store the greatest possible amount of potential energy in the cars.
(5) Still water behind a dam:
- It stores potential energy that is converted into kinetic energy when the water begins to fall through the dam