



 
We have two responses for you Kenneth, 60 watthours of electricity in one hour means 60 watthours per hour or 60 watthours/hour. If the bulb burns for 10 hours that's
Harley
Hi Kenneth. 1. Is this the same as (60 watthours) / (1 hour) or (60 watts) / (1 hour) or neither? The first. (60 watthours) / (1 hour) means the "hour" units cancel and you have 60 watts. That's a power rating. Watts are a power unit, Watthours (literally, this is watts times hours) are an energy unit. Thus, energy is power times time (E = Pt) A bulb is rated for a particular power (60 watts). If you run it for any period of time, it uses up energy (watthours, or kilowatthours if it is a particularly powerful bulb). If it helps, think about power like speed and energy like distance. A vehicle can go a particular speed and a bulb can burn at a certain power. If you multiply that by time, you get the total distance travelled or the total energy consumed. Power and energy really are quite different ideas and it is great that you are getting it straight! Cheers,  


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences. 