# How Do Potential Energy And Kinetic Energy Contrast Using One Example?

When discussing energy, there are two main types that are important to understand – potential energy and kinetic energy. Potential energy can be described as stored energy that has the potential to do work. A common example is the energy stored in a drawn back bow or slingshot. Kinetic energy is the energy of motion that an object has due to its movement. The faster or heavier an object is moving, the more kinetic energy it possesses.

## Roller Coaster Example

A roller coaster is a great real world example that shows the contrast between potential energy and kinetic energy. As the roller coaster train travels along the track, it converts back and forth between potential and kinetic energy while the total mechanical energy remains constant.

## Roller Coaster at Top of Hill

When a roller coaster reaches the top of a hill, it has maximum potential energy. Potential energy is energy that is waiting to be released. In the case of the roller coaster, the energy is stored based on the roller coaster’s height and mass. At the very top, the roller coaster is at its highest point above the ground. Gravity wants to pull the roller coaster down, but since it is still traveling upwards at the moment it reaches the top, that potential energy created by the height and mass has not yet begun converting into kinetic energy.

## Roller Coaster Going Down

As the roller coaster starts descending from the top of the hill, its potential energy begins converting into kinetic energy. The potential energy that the roller coaster accumulated at the top of the hill starts turning into motion energy. The roller coaster cart speeds up going down the hill as gravity accelerates it downward. The riders feel the thrill as it picks up speed. At any point as the roller coaster goes down, the sum of its potential and kinetic energy remains the same due to the law of conservation of energy. But the proportion shifts – as it loses potential energy, it gains an equal amount of kinetic energy causing it to accelerate more and more.

## Roller Coaster at Bottom

The roller coaster has reached the bottom of its descent and is accelerating due to gravity. At the bottom, the roller coaster has its greatest amount of kinetic energy. Kinetic energy is the energy an object has due to its motion. All of the potential energy the roller coaster built up at the top has been converted to kinetic energy moving the roller coaster down the hill and accelerating it due to gravity.

So at the bottom of the hill, the roller coaster is at its top speed and maximum kinetic energy. The potential energy is now at a minimum as there is very little elevation difference relative to the starting point. This contrasts with the top of the hill, where the roller coaster had maximum potential energy and close to zero kinetic energy.

## Roller Coaster Going Up

As the roller coaster begins going up the next hill, it is using the kinetic energy it gained while going down the previous hill to continue moving upwards against the force of gravity. The speed of the roller coaster slows down as it goes up the hill to the next peak point. At this point, potential energy is increasing while the kinetic energy is decreasing.

The conversion of kinetic energy back into potential energy demonstrates the conservation of energy principle. The total amount of mechanical energy in the roller coaster remains constant, even as the form of the energy transforms between kinetic and potential at different stages.

## Repeating Cycle

As the roller coaster travels through its course, energy continuously transforms back and forth between potential and kinetic energy in a repeating cycle. At the top of each hill, the roller coaster has maximum potential energy due to its height. As it travels down the hill gaining speed, this potential energy transforms into kinetic energy of motion. At the bottom of the hill, all the potential energy has transferred into maximum kinetic energy. As the coaster travels up the next hill, it loses speed as the kinetic energy transforms back into potential energy due to the increasing height. This back and forth transfer between potential and kinetic energy continues in a repeating cycle throughout the ride.

## Energy Conservation

An interesting phenomenon with the roller coaster example is that the total mechanical energy of the roller coaster remains constant at all points throughout its ride. Mechanical energy is the sum of an object’s kinetic energy and potential energy. At the top of the hill, the roller coaster has maximum potential energy due to its height but no kinetic energy because it’s momentarily at rest. As it travels down the hill it gains kinetic energy while losing potential energy. At the bottom of the hill its potential energy is at a minimum because it’s lowest to the ground, but its kinetic energy is maximized due to its high velocity. As it travels up the next hill it loses kinetic energy and gains potential energy once again. This transfer back and forth between potential and kinetic energy causes the total mechanical energy to remain constant. In essence, no mechanical energy is lost in the process. It is simply converted between potential and kinetic energy in a continuous cycle.

## Summary

As covered, potential energy refers to stored energy that has the potential to do work. Kinetic energy refers to energy in motion that is actively doing work. Using the roller coaster example, potential energy is at its maximum at the top of the hill where the roller coaster car is stationary. Kinetic energy is at its maximum going down the hill when the roller coaster car has the most velocity. The law of conservation of energy states that energy can transform between potential and kinetic, but the total amount of energy remains constant. So the roller coaster constantly exchanges potential and kinetic energy, with the total energy staying the same over one cycle from the top of a hill to the bottom and back up again. This demonstrates the contrast between potential and kinetic energy in a clear real-world example.

## Conclusion

To conclude, the comparison between potential and kinetic energy using the roller coaster example shows a repeating cycle of energy transformation. At the top of a hill, the roller coaster train has the maximum potential energy. As it travels down the hill gaining speed, this potential energy is transformed into kinetic energy. At the bottom, the train has maximum kinetic and minimum potential energy. As it travels up the next hill, it loses speed and kinetic energy which is converted back into potential energy. This cycle repeats over and over on the roller coaster track with energy continually changing forms between potential and kinetic but the overall mechanical energy remaining constant according to the principle of conservation of energy.

The key takeaways are that potential energy depends on an object’s height above the ground whereas kinetic energy depends on its speed. As one increases, the other decreases. Energy transforms between different forms which allows the roller coaster to operate, but the total amount stays the same. Understanding these energy concepts is important not just for roller coasters but for many mechanical systems and natural processes.