Power, Physics

Power:

The rate of doing work is called power, and it is defined as the work done in unit time.  As a formula, this would be:

power = work done/time Taken

 Power is expressed in several different units, such as the watt, ergs per second, and foot-pounds per second.  The most common unit of power in general use in the United States is the horsepower.  One horsepower (hp) is equal to 550 ft-lb's or 33000 ft-1b/min.  In the metric system the unit of power is the watt (W) or the kilowatt (kW).  One hp is equal to 746 watts; and 1 kW = 1.34 hp.

Example:

To compute the power necessary to raise an elevator containing 10 persons a distance of 100 ft in 5 s (assuming the loaded elevator weighs 2500 lb), proceed as follows:

Power = work done/Time Taken        = 2500 x 100/5                 = 50,000 ft-lb's/sec

 

    Since 1hp = 550 ft-lb's/sec then required hp = 50,000/550

      = 90.9 hp (67.81 kw assuming no friction losses)

 

 

Posted Date: 9/11/2012 6:27:03 AM | Location : United States







Related Discussions:- Power, Assignment Help, Ask Question on Power, Get Answer, Expert's Help, Power Discussions

Write discussion on Power
Your posts are moderated
Related Questions
Explain about the transmission electron microscope. The Transmission Electron Microscope Transmission electron microscopy (TEM) is a microscopy method; a beam of electrons i

Elastic collision : A collision is known as elastic when kinetic energy is also conserved along with the linear momentum. There is no transformation or loss of kinetic energy in th

What is the force required to accelerate a mass of one kilogram one meter per second per second? Basically, you have defined the Newton. Force is the vector product of mass



Armature core:    It houses the armature conductors or coils and causes them to rotate and as cuts the magnetic flux of field magnets. It also gives a path of very low reluctanc

Defective eyesight due to focusing(refractive)problems- ametropia: It is often possible to correct ametropia completely with glasses There are four general types of ametrop

a body is thrown horizontally with a velocity of u from the top of a tower. the displacement of the stone when the horizontal and vertical velocities are equal is

Question Put the different types of light in order from lowest frequency to highest frequency. Feedback: These are all instances of electromagnetic radiation. Elect

Explain the Thermodynamics - Heat and Work Thermodynamics is an area of science which looks at how changes in energy, work and the flow of heat influence each other. It can exp