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

Correct location of the image formed by a plane mirror, Presumptuous that i...

Presumptuous that it is understood that the object is in front of the mirror and anything on the other side of the mirror is behind the mirror is the following statement sufficient

Historical development of atomic models, Historical development of atomic m...

Historical development of atomic models In olden days there was an idea that all matter is made of tiny indivisible particles. When Thomson discovered electron, this idea

Transition temperature, Transition temperature It is temperature (based...

Transition temperature It is temperature (based on the substance involved) below which a superconducting substance conducts electricity with zero resistance; as a result, the t

Electric dipole, what are the subtopics of electric dipole with detail expl...

what are the subtopics of electric dipole with detail explain

What is the magnitude and direction of the velocity, A helicopter is ascend...

A helicopter is ascending vertically with a constant speed of 6 meters per second relative to the ground.  At the immediate the helicopter is 60 meters above the ground it rele

.gravitation, iif radius shrinks by 20% then what will be the effect on gra...

iif radius shrinks by 20% then what will be the effect on gravitational acceleration

What is the basic difference between current and voltage, They are exactly ...

They are exactly analogous to water pressure and water flow by a hose. That's why flowing electrons is known as a current, just like a water current. Voltage is the electromotiv

Explain transistor, Transistor: An active semi-conductor device with th...

Transistor: An active semi-conductor device with three terminals that is emitter base and collector is known as transistor. Types of Transistor: There are two types of

Rayleigh-jeans law, Rayleigh-Jeans law For any blackbody at thermodyna...

Rayleigh-Jeans law For any blackbody at thermodynamic temperature T, the radiancy R onto a range of frequencies among nu & nu + dnu is provided by R = 2 pi nu 2 k T/c 2 .

What is magnetic flux density?, It is defined as the magnetic lines of forc...

It is defined as the magnetic lines of force per unit area of the pole face.                                                    B=φ/A where φ is the magnetic lines of f

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