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

Fluid density and viscosity, The drag on a 30-ft long, vertical, 1.25-ft di...

The drag on a 30-ft long, vertical, 1.25-ft diameter pole subjected to a 30 mph air wind is to be determined with a model study. It is expected that the drag is a function of the p

Earth and moon two are act as a two magnets., Earth and Moon two are act as...

Earth and Moon two are act as a two magnets. and when they rotating the flux changes . then the current produces or not . if not what is the reason? Ans) E.M.F is induced only whe

Inclined plane frictionless motion help, A block initial located 3m up a fr...

A block initial located 3m up a frictionless inclined plane is given an initial velocity of 6m/s up the ramp. The plane is 10m long and titled by 30 degree. a) How long does it tak

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.

Describe the working of ultrasonic pulse echo system, Describe the working ...

Describe the working of ultrasonic pulse echo system. The working of ultrasonic pulse echo system: The ultrasonic pulse echo system is utilized to detect flaw, estimate the

Explain range of projectile, RANGE OF PROJECTILE:  "It is the horizonta...

RANGE OF PROJECTILE:  "It is the horizontal distance covered by the projectile from the point of projection to the point where it returns to its level of projection".

Explain laws of refraction, Laws of Refraction: There are two laws of r...

Laws of Refraction: There are two laws of refraction. The incident ray, the refracted ray and the normal to the surface of the point of incidence all lie at the similar plan

Define the principle and working of an a.c. generator., Define, with the he...

Define, with the help of diagram, the principle and working of an a.c. Generator. Write the expression for the e.m.f. generated in the coil in terms of its speed of rotation

Explain forward bias and reverse bias, Explain briefly, with the help of ci...

Explain briefly, with the help of circuit diagram, how V - I characteristics of a p-n junction diode are obtained ii (i) forward bias, and (ii) reverse bias. Illustrate th

Skin diease , which radio isotpo used in skin diease treatment

which radio isotpo used in skin diease treatment

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