# UKPCS Science: WORK POWER AND ENERGY: #11

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science (paper #6).

In physics, a force is said to do work if, when acting, there is a displacement of the point of application in the direction of the force. Work transfers energy from one place to another or one form to another. The SI unit of work is the joule (J), which is defined as the work expended by a force of one Newton through a displacement of one metre. The work done by a constant force of magnitude F on a point that moves a displacement s in a straight line in the direction of the force is the product W=Fs.

Work is closely related to energy. The work-energy principle states that an increase in the kinetic energy of a rigid body is caused by an equal amount of positive work done on the body by the resultant force acting on that body. Conversely, a decrease in kinetic energy is caused by an equal amount of negative work done by the resultant force.

The law of Conservation of Energy states that the total energy of an isolated system remains constant, it is said to be conserved over time. This law means that energy can neither be created nor destroyed; rather, it can only be transformed from one form to another.

In physics, power is the rate of doing work. It is the amount of energy consumed per unit time. Having no direction, it is a scalar quantity. In the SI system, the unit of power is the joule per second (J/s), known as the watt in honour of James Watt, the eighteenth-century developer of the steam engine. This new equation for power reveals that a powerful machine is both strong (big force) and fast (big velocity). A powerful car engine is strong and fast.

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