Explain the difference between potential energy and kinetic energy

Energy cannot be created or destroyed, meaning that the total amount of energy in the universe has always been and will always be constant. However, this does not mean that energy is immutable; it can change form and even transfer between objects. A common example of energy transfer that we see in everyday life is the transfer of kinetic energy—the energy associated with motion—from one moving object to a stationary object via work. In physics, work is a measure of energy transfer and refers to the force applied by an object over a distance. When a golf club is swung and hits a stationary golf ball, some of the club’s kinetic energy transfers to the ball as the club does “work” on the ball. In an energy transfer such as this one, energy moves from one object to another, but stays in the same form. A kinetic energy transfer is easy to observe and understand, but other important transfers are not as easy to visualize. Thermal energy has to do with the internal energy of a system due to its temperature. When a substance is heated, its temperature rises because the molecules it is composed of move faster and gain thermal energy through heat transfer. Temperature is used as a measurement of the degree of “hotness” or “coldness” of an object, and the term heat is used to refer to thermal energy being transferred from a hotter system to a cooler one. Thermal energy transfers occur in three ways: through conduction, convection, and radiation. When thermal energy is transferred bet...

Potential Energy What is potential energy? Potential energy is the stored energy an object has because of its position or state. A bicycle on top of a hill, a book held over your head, and a stretched spring all have potential energy. How to Measure Potential Energy The standard unit for measuring potential energy is the joule, which is abbreviated as "J." How is it different from kinetic energy? Potential energy is stored energy while kinetic energy is the energy of motion. When potential energy is used it is converted into kinetic energy. You can think of potential energy as kinetic energy waiting to happen. The green ball has potential energy due to its height. The purple ball has kinetic energy due to its velocity. A Car on a Hill We can compare potential and kinetic energy by considering a car on a hill. When the car is at the top of the hill it has the most potential energy. If it is sitting still, it has no kinetic energy. As the car begins to roll down the hill, it loses potential energy, but gains kinetic energy. The potential energy of the position of the car at the top of the hill is getting converted into kinetic energy. Gravitational Potential Energy One type of potential energy comes from the Earth's gravity. This is called gravitational potential energy (GPE). Gravitational potential energy is the energy stored in an object based on its height and mass. To calculate the gravitational potential energy we use the following equation: GPE = mass * g * height GPE...

Learning Objectives By the end of this section, you will be able to: • Define electric potential and electric potential energy. • Describe the relationship between potential difference and electrical potential energy. • Explain electron volt and its usage in submicroscopic process. • Determine electric potential energy given potential difference and amount of charge. When a free positive charge q q is accelerated by an electric field, such as shown in q q by the electric field in this process, so that we may develop a definition of electric potential energy. Figure 19.2 A charge accelerated by an electric field is analogous to a mass going down a hill. In both cases potential energy is converted to another form. Work is done by a force, but since this force is conservative, we can write W = –Δ PE W = –Δ PE. The electrostatic or Coulomb force is conservative, which means that the work done on q q is independent of the path taken. This is exactly analogous to the gravitational force in the absence of dissipative forces such as friction. When a force is conservative, it is possible to define a potential energy associated with the force, and it is usually easier to deal with the potential energy (because it depends only on position) than to calculate the work directly. We use the letters PE to denote electric potential energy, which has units of joules (J). The change in potential energy, Δ PE Δ PE, is crucial, since the work done by a conservative force is the negative of the...

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