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

Can you explain modulation, Can you explain modulation? Why is it required...

Can you explain modulation? Why is it required? What is "World Wide Web" (WWW)? Give the frequency range of speech signals.

Curie-weiss law, Curie-Weiss law (P. Curie, P.-E. Weiss) A more genera...

Curie-Weiss law (P. Curie, P.-E. Weiss) A more general shape of Curie's law, that states that the susceptibility, khi, of an paramagnetic substance is associated to its thermo

What is modern view, What is Modern view Modern view : It objects tend...

What is Modern view Modern view : It objects tend to remain in their initial state; force is needed to change motion. Resistance to alters in motion is known as inertia.

Heat transfer, You just need to use numerical methods to find temperature d...

You just need to use numerical methods to find temperature distribution in two or three dimensional plate; cylinder, sphere or you can model heat flow in any geometry with boundary

For 9th, can i get this job?

can i get this job?

Interference and diffraction, INTERFERENCE and DIFFRACTION: INTERFEREN...

INTERFERENCE and DIFFRACTION: INTERFERENCE: The physical effect of super position of waves from two sources vibrating with same frequency and amplitude is called the interfere

Calculate percentage, By what percentage should the pressure of a given mas...

By what percentage should the pressure of a given mass of gas be increased,so as to decrease its volume  by 10% at a constant temperature.

Find the shell temperature, Q. Find the shell temperature? In a shell-a...

Q. Find the shell temperature? In a shell-and-tube heat exchanger, one fluid passes through a central tube while another fluid flows through an outer shell in the opposite dire

Write an equation expressing interest rate, Q. Assume an economy is in a li...

Q. Assume an economy is in a liquidity trap. A. Write an equation expressing interest rate parity under a fixed exchange rate regime. Answer: Liquidity trap entail R = 0

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