A collision of swimming pool balls is an example of kinetic power being transferred from one object to another.(Image credit: FikMik | Shutterstock)
Kinetic energy is the power of massive in motion. The kinetic power of an object is the power it has due to the fact that of the motion.

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In Newtonian (classical) mechanics, which defines macroscopic objects relocating at a small fraction of the rate of light, the kinetic energy (E) the a enormous body in motion have the right to be calculation as fifty percent its massive (m) time the square that its velocity (v):E = ½mv2. Note that energy is ascalarquantity, i.e., that does not depend on direction, and it is constantly positive. Once we dual the mass, we double the energy; however, when we double the velocity, energy increases through a factor of four.

acquire to work

Perhaps the most crucial property that kinetic energy is its capability to dowork. Work is identified as force acting on things in the direction of motion. Occupational andenergyare so very closely related as to be interchangeable. While energy of movement is normally expressed asE= ½mv2, work-related (W) is an ext often assumed of as pressure (F) times distance (d):W=Fd. If we want to change the kinetic power of a substantial object, we must do occupational on it.


For example, in order come lift a hefty object, we have to do work to get rid of the force because of gravity and move the thing upward. If the thing is double as heavy, it takes double as much work to lift that the exact same distance. It likewise takes double as much work to lift the same object twice as far. Similarly, to slide a heavy object throughout a floor, we have to overcome the force offrictionbetween the object and also the floor. The work required is proportional to the load of the object and also the distance it is moved. (Note that if you room carrying a piano top top your earlier down a hallway, you space not in reality doing any kind of real work.)


Potential energy

Kinetic energy can it is in stored. For example, it takes work-related to elevator a weight and also place the on a shelf or come compress a spring. What wake up to the energy then? We know that energy is conserved, i.e., it cannot be created or destroyed; it have the right to only be converted from one type to another. In these two cases, the kinetic power is convert topotentialenergy due to the fact that while the is no actually act work, it has actually the potential to execute work. If us drop the object from the shelf or relax the spring, the potential power is converted back into kinetic energy.


Kinetic energy can likewise be moved from one human body to one more in a collision, which can beelasticorinelastic. One example of one elastic collision would certainly be one billiard sphere striking another. Skipping the friction in between the balls and also the table or any type of spin imparted come the cue ball, ideally the full kinetic power of the two balls after ~ the collision is same to the kinetic power of the cue ball before the collision.

An instance of an inelastic collision could be a moving train auto bumping into a comparable stationary car and also coupling come it. The full energy would stay the same, however the mass of the new system would be doubled. The result would it is in the two cars continuing in the same direction at a reduced speed such thatmv22= ½mv12, wheremis the fixed of one car,v1is the velocity that the very first car, andv2is the velocity of the combination cars after the collision. Splitting bymand taking the square source of both sides we getv2= √2/2∙v1. (Note thatv2≠ ½v1.)

Additionally, kinetic power can be converted right into other develops of energy and also vice versa. For example, kinetic energy can be convert into electric energy through a generator or into thermal power by the brakes ~ above a car. Conversely, electric energy deserve to be converted earlier to kinetic energy by an electric motor, thermal power can be converted to kinetic energy by a heavy steam turbine, and chemical energy can be convert to kinetic power by one internal combustion engine.

Jim Lucas is a freelance writer and editor specializing in physics, astronomy and also engineering. That is basic manager ofLucas Technologies.

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Jim Lucas is a contributing writer because that Live Science. The covers physics, astronomy and also engineering. Jim graduated from Missouri State University, wherein he deserve a bachelor of science degree in physics through minors in astronomy and technical writing. After graduation he worked at Los Alamos national Laboratory as a network solution administrator, a technical writer-editor and also a nuclear security specialist. In addition to writing, the edits scientific journal write-ups in a range of subject areas.