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

Einstein''s Theory of Relativity, According to Einstein''s Theory of Relati...

According to Einstein''s Theory of Relativity, would time be able to be expressed as a binary system, with a + 1 as yes, a - 1 as a no, and a 0 as an unanswered question?

Find the minimum wavelength of x-rays, Q. Find the minimum wavelength of X-...

Q. Find the minimum wavelength of X-rays produced by an X-ray tube operating at 1000 kV. λmin = 12400 A 0 / V Therefore λmin = 12400 X 10 -10 / 10 6 = 0.0124 A 0

What is rarer and denser medium , A medium is known as denser if the veloci...

A medium is known as denser if the velocity of ray in that phase is fewer than the speed of the wave in other phase.     In comparison to air velocity of sound is main in water,

Electricity, when to identical cells are connected either in series or para...

when to identical cells are connected either in series or parallel across a 2 ohm resistor they send the same current through it calculate the internal resistance of each cell?

Ultrasonics, Industrial applications of ultrasonics

Industrial applications of ultrasonics

How does the elevation affect the boiling point of water, How does the elev...

How does the elevation and air pressure affect the boiling point of water? The only factor that explains the boiling point of water at any altitude is the barometric pressure (

The stoplight- 1-dimensional kinematics, The Stoplight- 1-Dimensional Kinem...

The Stoplight- 1-Dimensional Kinematics A blue car moving at a constant speed of 10 m/s passes a red car which is at rest. This occurs at a stoplight the moment in which the li

., why is nichrome wire used in electric heaters? properties of nichrome wi...

why is nichrome wire used in electric heaters? properties of nichrome wire.

Work, what is the work done of a man standing on a height of 13 meter holdi...

what is the work done of a man standing on a height of 13 meter holding a bag of 6 kg

Is it magnetism imp for iiit?, Yes magnetism more important for iit because...

Yes magnetism more important for iit because the weight of this magnetism is very hign so be careful about this magnetism chapter All the best for your preparation

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