# Weight to watt conversion

1. Feb 16, 2009

### andyc

How do I figure out how many watts per hour or horse power it takes to lift a 200 pound mass using electro magnet? Is there a formula I can use? Thanks for any help

2. Feb 16, 2009

### Staff: Mentor

Welcome to the PF. First, Watts is already a measure of power. Power is energy per time, and 1 Watt = 1 Joule per second.

It's easiest to work in mks (meters, kilograms, seconds) units, so you should try to convert your units to mks and stay consistent with the units.

The work done (energy invested) in lifting something against the force of gravity can be determined by the mass of the object and its final height:

PE = mgH (Potential Energy = mass * g * Height), where g = 9.8m/s^2 is the acceleration due to gravity

You would calculate that (all in mks units), and that gives you the change in energy, or the work done to lift the mass.

The faster you want to lift the object to that height, the more power it takes, because:

P = W / t (Power in Watts = Work in Joules * time in seconds)

And finally, once you have your answer in Watts, you can use the conversion:

1 horsepower = 750 Watts.

Show us your work as you do the calculations, and we can check it for you. You can google "mks calculator" to get some help with the unit conversion if you need it.