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Course: Middle school physics>Unit 3

Lesson 2: Potential energy

Potential energy

Potential energy is the stored energy in an object due to its position, properties, and forces acting on it. Common types of potential energy include gravitational, elastic, magnetic, and electric. These energies relate to an object's position or shape, and their potential to convert into kinetic energy. Created by Khan Academy.

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• What is the difference between electric potential energy and electric forces? Both of them have the same thing: Opposites attract, and similarities repel.
• Hey,
You have the basic idea: opposites charges attract and similar charges repel.

However, electric potential energy is the energy needed to move a charge against an electric field. Imagine that the Earth is a positively charged ball. Now all positive ions would move away from the Earth, naturally, so the question would be how much work would be needed to move a positive ion towards the Earth.

It would be similar to thinking about gravitational potential energy but reversed, because now (in Electrical Potential Energy) energy is needed to move a positive ion toward the "ball" not away.

So, in summary, both ideas revolve around the fact of opposites charges attract and similar charges repel. But, electric potential energy develops on that basic idea and is the amount of stored energy (potential energy) when two similarly charged ions are moved closer to each other.

Hope that helps.
• A good way of seeing it is theoretical energy or am I wrong?
• Yes, that’s a good way of seeing it. Potential energy is a type of energy that is stored in an object due to its position relative to other objects. It is theoretical energy because it has the potential to become kinetic energy.
• How does Earth 🌍 attract an object from space? Why doesn’t that happen when a rocket ship is launched?
• Earth attracts objects using gravitational force; a rocket ship does get attracted to Earth through gravitational force, which is why it must have hundreds of tons of fuel to generate enough force to propel it out of the atmosphere and counteract Earth’s gravitational pull.
• In school I learned that there is also chemical potential energy. How does that work?
• You are correct. Chemical potential energy is the energy stored in the chemical bonds of a substance. When the substance undergoes a chemical reaction, the bonds are broken and the energy is released. This energy can be used for various purposes, such as powering a car engine or heating a house1.

For example, gasoline contains a large amount of chemical potential energy that is released when it is burned in a controlled way in the engine of a car2.

I hope this helps. Let me know if you have any other questions.
• What is potential energy
(1 vote)
• When energy is stored in something
• What is the difference between gravitational forces and gravitational potential energy?
(1 vote)
• The gravitational force only depends on the mass of an object. The gravitational potential energy depends on both the mass as well as its position. Gravitational force is the pull on the object, or its weight. Gravitational potential energy is the potential to do work because of its position
• How do you know if an object is negative or positive electric charged?
• I think I understand the elastic potential energy, but I don't really get why the further from Earth something is, the more potential energy it has. Shouldn't there be less potential energy? Because the gravitational pull gets smaller the further you get from it. Same thing for magnetic and electric potential energy.
• You're half right. Yes, when on abject gets further from earth, it's less effected by gravity, but it is still moving towards earth. Think about it this way: If you had an object 1 foot above earths surface it would have a little bit of potential energy because, if you were to let it go, it would fall towards earth at a certain speed, but only for one foot. Now if you had an object 1 mile above Earth's surface it would have even more potential energy because, if you dropped it, it would fall to the earth for an entire mile, gaining much more speed and much more kinetic energy than if was dropped at 1 foot. So the further away it is, the faster it will be able to go towards Earth and the more potential energy it has. I hope this helped!
• I’m so bad at physics, too
• I'm terrible, since I keep getting mixed up with electromagnetic properties and whatnot :)
(1 vote)
• is potential energy real?
wouldn't gravitational potential energy be based on the center of mass of earth, not how close it is from the surface?