Power, Physics

Assignment Help:

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)

 

 


Related Discussions:- Power

Frequency dependence of dielectric constant, E lectrons have very much smal...

E lectrons have very much smaller mass than that of ions, so they respond more rapidly to a changing electric field. For electric field that oscillates at extremely high frequencie

Calculate the speed and frequency of elctromagnetic wave, Imagine an elctro...

Imagine an elctromagnetic wave propagating vacuum with electric field Ex=10 2 sinπ(3x10 6 z - 9x10 14 t) V/m, E y =0, E z = 0. Calculate the speed, frequency, wavelength, initial

Ammeter, what happened if we connect ammeter parallel to the resistor, whos...

what happened if we connect ammeter parallel to the resistor, whose current we wnt to find ,rather than in series?

How to calculate n factor of disproportion reaction, How to calculate n fac...

How to calculate n factor of disproportion reaction? Total number of electron change divided by no. of moles of reactant This is conventional method Total electron chan

Extrapolate the experimental data to predict the pressure, Water at 20°C fl...

Water at 20°C flows through a long, straight pipe. The pressure drop is measured along a section of the pipe of length 1.3 m as a function of average velocity through the pipe. Res

Draw a schematic diagram of a single optical fibre structure, Draw a schema...

Draw a schematic diagram of a single optical fibre structure. Describe briefly how an optical fibre is fabricated. Explain in brief, the mechanism of propagation of light signal by

State laws of motion, 1. Every object in a state of uniform motion tends to...

1. Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. II. The relationship between an object''s mass m,

Image formation for concave mirrors - case a, Image Formation for Concave M...

Image Formation for Concave Mirrors - Case A To look an object within any type of mirror, a person must sight along a line at the image of the object. Whole persons capable of

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd