Kinetic and Potential Energy

Your knowledge of kinetic and Potential Energy is tested on the GED science test.

This lesson is a part of Onsego GED Prep.

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Kinetic energy is the energy an object has because it’s moving. Think about a speeding car, a rolling ball, or a running person. The faster they go and the heavier they are, the more kinetic energy they have. For example, a fast-moving car has more kinetic energy than a slow-moving bicycle, and a heavy truck has more kinetic energy than a light motorcycle moving at the same speed.

Potential energy, on the other hand, is the energy stored in an object because of its position or height. Imagine holding a book up high or a roller coaster at the top of a hill. The higher the object, the more potential energy it has. When you lift a book to a shelf, it has potential energy because of its height. Similarly, a roller coaster has a lot of potential energy at the top of a hill, which transforms into kinetic energy as it speeds down.

To illustrate, consider a roller coaster at the top of a hill. At this point, it has maximum potential energy because it is at its highest point. As it moves down the hill, this potential energy is converted into kinetic energy, making the roller coaster speed up. At the bottom of the hill, the potential energy is zero because it is at the lowest point, but the kinetic energy is at its maximum due to its speed.

In the GED science test, you will be asked to calculate kinetic or potential energy, and you will always be provided with the formulas. Let’s take a look at how to do it.

To figure out kinetic energy, we use a simple formula: KE = 1/2 × mass × velocity squared. KE stands for kinetic energy. Mass is how much stuff is in the object, measured in kilograms (kg). Velocity is how fast the object is moving, measured in meters per second (m/s).

Let’s walk through an example together. Imagine a car that weighs 1,000 kg and is moving at 10 m/s. We want to find out its kinetic energy. First, we take the mass, which is 1,000 kg. Next, we take the speed, which is 10 m/s, and square it. Squaring means multiplying it by itself, so 10 times 10 equals 100. Then, we multiply the mass by this squared speed: 1,000 times 100 equals 100,000. Finally, we take half of that number because there is ½ at the beginning of the formula. So, half of 100,000 is 50,000. The car’s kinetic energy is 50,000 joules.

To figure out potential energy, we use a different formula: PE = mgh. PE stands for potential energy. Mass is how much stuff is in the object, measured in kilograms (kg). g is the acceleration due to gravity, which is always 9.8 meters per second squared. Height is how high the object is, measured in meters (m).

Let’s look at an example. Imagine you lift a book that weighs 2 kg to a shelf that is 3 meters high. We want to find out its potential energy. First, we take the mass, which is 2 kg. Next, we take the height, which is 3 meters. We also use the acceleration due to gravity, which is 9.8 m/s². Then, we multiply these numbers together: 2 kg × 9.8 m/s² × 3 m = 58.8 joules. So, the book’s potential energy is 58.8 joules.

Sometimes, on the GED science test, you might need to find the difference in potential energy between two heights. Let’s take a look at this sample question.

The potential energy (in Joules) of a pendulum at a certain height is given by the following equation: PE = mgh. If a pendulum has a mass of 2 kg, what is the difference in potential energy (Joules) between the pendulum at heights of 1 meter and 1.5 meters?

A) 4.9
B) 9.8
C) 14.7
D) 19.6

Correct Answer: B) 9.8

Explanation:

To find the potential energy at each height, use the formula:

For height 1 meter: PE = 2 kg × 9.8 m/s² × 1 m = 19.6 J

For height 1.5 meters: PE = 2 kg × 9.8 m/s² × 1.5 m = 29.4 J

Difference in potential energy: 29.4 J minus 19.6 J = 9.8 J

So, the difference in potential energy is 9.8 Joules.

You might also come across a different formula for potential energy, especially related to springs. The formula for the potential energy stored in a spring is PE = 1/2 k x squared, where k is the spring constant (measured in N/m), and x is the stretch distance (measured in meters). This formula is used when dealing with elastic potential energy, such as in springs. To calculate the potential energy, you simply plug in numbers as we did before.

Last Updated on October 20, 2025.