Kinetic energy is the energy of motion. Any object that is moving possesses kinetic energy. Baseball involves a great deal of kinetic energy. The pitcher throws a ball, imparting kinetic energy to the ball. When the batter swings, the motion of swinging creates kinetic energy in the bat. The collision of the bat with the ball changes the direction and speed of the ball, with the idea of kinetic energy being involved again.
As stated in the kinetic-molecular theory, the temperature of a substance is related to the average kinetic energy of the particles of that substance. When a substance is heated, some of the absorbed energy is stored within the particles, while some of the energy increases the motion of the particles. This is registered as an increase in the temperature of the substance.
At any given temperature, not all of the particles of a sample of matter have the same kinetic energy. Instead, the particles display a wide range of kinetic energies. Most of the particles have a kinetic energy near the middle of the range. However, a small number of particles have kinetic energies a great deal lower or a great deal higher than the average (see figure below). Figure \(\PageIndex{2}\): A distribution of molecular kinetic energies as a function of temperature. The blue curve is for a low temperature, while the red curve is for a high temperature. (Credit: Christopher Auyeung; Source: CK-12 Foundation; License: CC BY-NC 3.0(opens in new window))The blue curve in the figure above is for a sample of matter at a relatively low temperature, while the red curve is for a sample at a relatively high temperature. In both cases, most of the particles have intermediate kinetic energies, close to the average. Notice that as the temperature increases, the range of kinetic energies increases and the distribution curve "flattens out". At a given temperature, the particles of any substance have the same average kinetic energy.
As a sample of matter is continually cooled, the average kinetic energy of its particles decreases. Eventually, one would expect the particles to stop moving completely. Absolute zero is the temperature at which the motion of particles theoretically ceases. Absolute zero has never been attained in the laboratory, but temperatures on the order of \(1 \times 10^{-10} \: \text{K}\) have been achieved. The Kelvin temperature scale is the scale that is based on molecular motion, and so absolute zero is also called \(0 \: \text{K}\). The Kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles of the substance. For example, the particles in a sample of hydrogen gas at \(200 \: \text{K}\) have twice the average kinetic energy as the particles in a hydrogen sample at \(100 \: \text{K}\). Figure \(\PageIndex{3}\): Helium gas liquefies at \(4 \: \text{K}\), or four degrees above absolute zero. Liquid helium is used as a coolant for large superconducting magnets, and must be stored in insulated metal canisters. (Credit: Michael Pereckas (Flickr: Beige Alert); Source: http://www.flickr.com/photos/beigephotos/5633215176/(opens in new window); License: CC BY 2.0(opens in new window))Summary
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Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses No worries! We‘ve got your back. Try BYJU‘S free classes today! Open in App Suggest Corrections 3 Bianca J. 2 Answers By Expert Tutors
Paige B. answered • 01/09/20 Current Chemistry Major at Stony Brook University
As heat is added to a system, the molecules move faster and faster. Since kinetic energy is seen as the energy of motion, increasing the temperature, increases kinetic energy. Think about ice compared to water compared to water vapor. The molecules in ice are very close together and relatively still, but as you add heat (increase the temperature), the molecules begin to move (vibrating,rotating,etc.) and gain kinetic energy. This cause the molecules to push away from each other which is why water vapor takes up more volume than ice.
Jesse E. answered • 01/09/20 Masters in Chemistry and Bachelors in Biology
Great question and important concept in chemistry. The temperature of a substance is directly related to its kinetic energy. Because kinetic energy is the energy a substance has because of its molecules being in motion, as a substance absorbs heat its molecules move faster, thereby increasing the substance's kinetic energy. For example, think of a water on placed on the stove. As the water is heated, more energy is transferred to water. Because its kinetic energy has increased, the temperature rises. |