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

Magnetic poles, Magnetic poles: The two regions near the ends of a magn...

Magnetic poles: The two regions near the ends of a magnet at which the attracting forces appear to be concentrated are called the magnetic poles. The pole (when freely suspende

Variation of temperature according to newton''s law, Variation of temperatu...

Variation of temperature of a body according to Newton's law: Let Consider a system has a temperature Φi at time t = 0. It is placed in an environment whose temperature is Φ0. We a

Why x-rays are not used in microscopes, Q. Why X-rays are not used in micro...

Q. Why X-rays are not used in microscopes? 1) The wavelength of X-rays is slighter than that of the visible light. 2) X-rays can't be focussed as visible radiations are foc

Explain average velocity, AVERAGE VELOCITY: The ratio of the total disp...

AVERAGE VELOCITY: The ratio of the total displacement to the total time taken by the body is known as average velocity and represented by V ?av.

Explain battery powered vehicles, Battery powered vehicles Used DC seri...

Battery powered vehicles Used DC series motors are the first choice. Recently AC motors with frequency changers are being considered.

What are the applications of heterojunction laser, What are the application...

What are the applications of Heterojunction Laser? Applications of Heterojunction laser: a. Into consumer electronics, semiconductor lasers are utilized in VCD/CD /DVD playe

Decade resistor, DECADE resistors are wire wound resistors. These are wound...

DECADE resistors are wire wound resistors. These are wound on cards moulded on round a switch of low contact resistance. Alloys used for wire are Manganin, minalpha, etc. Bifilar w

What is emission spectrum, When wave emitted by a self luminous object is d...

When wave emitted by a self luminous object is dispersed by a prism to get the spectrum, the spectrum is known as emission spectrum.

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