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

Nearly free electron model, how cah i get the band gap by considering a wav...

how cah i get the band gap by considering a wavefunction including bloch function

Electricity, help by post offoce box explan rasistance of a wire

help by post offoce box explan rasistance of a wire

Biot law, what is the biot law give the mathmatical description.

what is the biot law give the mathmatical description.

Expermient of containers from used electric bulbs, Containers from used ele...

Containers from used electric bulbs Used electric light bulbs can be made into containers that will substitute for flasks, beakers, test tubes and same devices. With reasonable

An example of change in the momentum, A girl throws a 0.1 kilogram ball at ...

A girl throws a 0.1 kilogram ball at a wall.  The ball hits the wall perpendicularly with a velocity of 5 meters per second and then bounces straight back with a velocity of 4 mete

Determine the maximum value of flux density in the core, A single-phase, 50...

A single-phase, 50Hz transformer has 40 primary turns and 520 secondary turns. The cross-sectional area of the core is 270cm 2 . When the primary winding is connected to a 3

What do you mean by lateral shift, Q. What do you mean by lateral shift? an...

Q. What do you mean by lateral shift? and What could be the angle of incidence to have maximum lateral shift? Q. For what angle, lateral shift is minimum?

Ametropia-defective eyesight due to focusing, Defective eyesight due to foc...

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

Whta is mach number , Mach number is the ratio of velocity of source to the...

Mach number is the ratio of velocity of source to the velocity of sound.        Mach Number = Velocity of Source / Velocity of Sound  .

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