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

Explain about the piezoelectric effect, Explain about the piezoelectric eff...

Explain about the piezoelectric effect. Piezoelectric effect: While crystals as quartz or tourmaline are stressed beside any pair of opposite faces, electric charges of oppo

top of the window, A stone drops from the edge of the roof. It passes the ...

A stone drops from the edge of the roof. It passes the window 2 m high in 0.1s . How far is the roof above the top of the window? Solution) Height of the window (h) = 2m Acce

Thermodynamic laws, Thermodynamic laws: First law of thermodynamics ...

Thermodynamic laws: First law of thermodynamics In internal energy of a system the change is the total heat transferred to or from the system & the work done on or by

Evaluate the maximum work done, 10 moles of an ideal gas expands reversibly...

10 moles of an ideal gas expands reversibly and isothermally from a volume if 5 lit. to 50 lit. at 25°C. Find the maximum work done? Express the result in Joules.

Describe the resolution of the scanning electron microscope, Describe the r...

Describe the resolution of the scanning electron microscope. Resolution of the SEM (scanning electron microscope): The spatial resolution of the SEM depends onto the size of

How does laser printer works, How does laser printer works? When a text...

How does laser printer works? When a text or image is entered into the CPU, it makes a series of varying voltages. This controls a LED (light emitting diode) in the printer. Th

What is sarah horizontal acceleration, Alfonso and Sarah like to go sky div...

Alfonso and Sarah like to go sky diving together. Alfonso has a mass of 88 kg, and Sarah has a mass of 66 kg. While in free fall together, Alfonso pushes Sarah horizontally with a

Can you explain doppler effect, Can you explain Doppler effect? Find a math...

Can you explain Doppler effect? Find a mathematical expression for the apparent frequency heard when the source is in motion and the listener is at rest and also give limitation of

Determine joules of heat if energy dissipated by resistor, The potential di...

The potential difference across a 4 ohm resistor is 20 volts.  Assuming that all of the energy dissipated by this resistor is in the form of heat, how many joules of heat are radia

Process to calculate teh number of atoms per unit cell, Process to calculat...

Process to calculate teh number of atoms per unit cell The number of atoms per unit cell is equal to the product of 'the number of atoms per basis' and 'the number of basis per

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