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

Sound problem, A Decibel meter reads 140 dB for a sound source at 20''c at...

A Decibel meter reads 140 dB for a sound source at 20''c at 60 % relative humidity. It also records sound pressure for 140 dB as 200 pascals what will it read( decibel meter) at 4

Evaluate the period of simple harmonic motion, A simple pendulum is 4.00 m ...

A simple pendulum is 4.00 m long. (a) What is the period of simple harmonic motion for this pendulum if it is hanging in an elevator accelerating upward at 7.00m/s 2 ? (b) Wha

How high does the seawater rise in the bell, A cylindrical diving bell 2.00...

A cylindrical diving bell 2.00 min diameter and 5.00 m tall with an open bottom is submerged to a depth of 220 m in the ocean. The surface temperature is 25.0°C, and the temperatur

Michelson interferometer, Ask question 15. When the movable mirror of a Mic...

Ask question 15. When the movable mirror of a Michelson''s interferometer is moved through a distance of 0.03mm, 100 fringes are displaced, what is the wavelength and color of the

Define rms value of ac, Q. Define: rms value of AC. RMS value of a.c...

Q. Define: rms value of AC. RMS value of a.c. The rms value of alternating current is described as that value of the steady current which when passed through a resisto

Can a solid as well as liquid together be possible, Q. Can a solid as well ...

Q. Can a solid as well as liquid together be possible? Answer:- In reality substances can exist in all three states of matter simultaneously if the conditions are right. T

State the demerits of semiconductor diode over vacuum diode, Demerits of Se...

Demerits of Semiconductor Diode over Vacuum Diode (i)  It can't withstand high reverse voltage (ii)  It can't operate at fairly high temperatures.

Which phrase would be incorrect to use, Which phrase would be incorrect to ...

Which phrase would be incorrect to use: (1)A molecular of a compound  (2)A molecule of an element (3)An atom of an element (4)None of these Ans:  (2)A molecule of a

Define gas in harmonic well, Define Gas in Harmonic Well? A classical ...

Define Gas in Harmonic Well? A classical system of N distinguishable no interacting particles of mass m is placed in a three-dimensional harmonic well: a) Discover t

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