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

Mechanics, to derive expreation for magnitude & direction for the resultant...

to derive expreation for magnitude & direction for the resultant which two are acting at a point

Theory to calculate magnetic moment of a bar magnet, Illustrate ‘tan A ‘and...

Illustrate ‘tan A ‘and ‘tan B' positions of a deflection magnetometer. Illustrate the theory to calculate magnetic moment of a bar magnet and Horizontal component of the earths

Must all illuminator have forced ventilation, Must all illuminator have for...

Must all illuminator have forced ventilation? Usually yes, the exception being which with a massive construction that dissipate heat by transfer or radiation.

Applications/uses of transformers, (1)         F or supplying power from ...

(1)         F or supplying power from on alternating current power grid to equipment which uses a different voltage. (2)         Electrical power transmission over long dist

Friction a necessary evil, Friction has several disadvantages but life is i...

Friction has several disadvantages but life is impossible without friction because friction has many benefits also.

Gauss divergence theorem, Using Gauss divergence theorem show that the volu...

Using Gauss divergence theorem show that the volume of a sphere of radius 'r' is 4⁄3 πr 3 .

Bulky group present at axial position , Why bulky group present at axial po...

Why bulky group present at axial position of chair or boat conformer is less stable compared to equitorial position?  Ans) Let the bulky group has a large mass M. suppose it is

Explain about the term step index fibre, Explain about the term step index ...

Explain about the term step index fibre. Step index fibre: Into a step index fibre, the refractive index keeps constant throughout the core and decreases at the core-claddin

Centre of the square, Fig- detremines a square loop Made from a uniform wir...

Fig- detremines a square loop Made from a uniform wire. Determine the magnetic field at the centre of the square if a battery is connected among the points A and C.

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