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

Calculate the emf induced between the ends of the wings, Q. An aircraft hav...

Q. An aircraft having awing span of 10 m flies at a speed of 720 kmph. If the vertical component of the earth's magnetic field is 3 X 10 -5 T, calculate the emf induced between th

Motion in one dimension, an attacker at the base of a castle wall 3.65 m hi...

an attacker at the base of a castle wall 3.65 m high throws a rock straight up with speed 7.40 m/s at a height of 1.55 m above the ground. (a) will the rock reach the top of the wa

Si unit of force, UNIT: SI unit of force is Newton (N).

UNIT: SI unit of force is Newton (N).

Stopping distance of a hot wheels car-work and energy, Stopping Distance of...

Stopping Distance of a Hot Wheels Car While the Hot Wheels car collides along with the box and skids to a stop, external forces do an important amount of work upon the car. The

Motion in one dimension, what is the discussion of motion in one dimension ...

what is the discussion of motion in one dimension for experiment 7

Newton''s Second Law, What is the acceleration due to gravity and does the ...

What is the acceleration due to gravity and does the number ever change on earth

PHYSICS, WHAT IS THE MEAN OF HEAT

WHAT IS THE MEAN OF HEAT

Electric, The P.D. at the feeder end of a two wire d.c. distributor is 600...

The P.D. at the feeder end of a two wire d.c. distributor is 600 volts. Two loads are connected to the distributor at distances of 600 feet and 1000 feet from the feeder end and t

Semiconductor materials: cadmium sulphide, Energy gap: 2.4ev.   The...

Energy gap: 2.4ev.   The colour of pure cadmium sulphide is pale yellow. It melts only under at high temperature. It can be prepared in the resistivity range from 10 to

Inertia with a stone, Inertia with a stone You will require a stone wei...

Inertia with a stone You will require a stone weighing about 1 kg for this experiment. Wrap a length of heavy string about the stone. Now, on opposite sides of the stone, join

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