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

Truck and the ball- vectors and projectiles, Truck and The Ball Suppose...

Truck and The Ball Suppose a pickup truck moving along with a constant speed along a city street. Within the course of its motion, a ball is projected straight upwards through

Obt, Obtain expression for an optical path difference for formation of circ...

Obtain expression for an optical path difference for formation of circular fringe in Michelson''s interferometer

Interference, Construction and working of Fabry perot interferometer

Construction and working of Fabry perot interferometer

What is the length of the string, The mass of a string is 4.20 x 10 -3 kg,...

The mass of a string is 4.20 x 10 -3 kg, and it is stretched so the tension in it is 135 N. A transverse wave traveling on this string has a frequency of 260 Hz and a wavelength o

Viscosity of liquid, How to determine the co efficient of viscosity of liqu...

How to determine the co efficient of viscosity of liquid by capillary flow method?

Evaluate the skier''s height h, A water skier lets go of the tow rope upon ...

A water skier lets go of the tow rope upon leaving the end oaf jump ramp at a speed of 14.0 m/s. The skier has a speed of 13.0m/s at the highest point of the jump. Ignoring air res

What are sheathed fibers, What are sheathed fibers? The optics, which h...

What are sheathed fibers? The optics, which has an external cladding whether transparent or opaque, affords a mechanical protection to the optics.

A simple model of the earth and moon, A simple model of the earth and moon ...

A simple model of the earth and moon The earth can be shown by an orange or other round object stuck on a piece of bamboo or a meat skewer. A piece of bent wire or knitting nee

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