# Webassign due in like half hour! i have the problem down but its not working

1. Mar 17, 2008

### lettertwelve

webassign due in like half hour! i have the problem down...but its not working!!!

1. The problem statement, all variables and given/known data

A steam iron draws 8.0 A when connected to a potential difference of 120 V.
(a) What is the power rating of this iron? 960 W <<<<correct

(b) How many joules of energy are produced in 20.0 min?
320 J <<<incorrect why???

(c) How much does it cost to run the iron for 20.0 min at $0.010/kW·h? .0032$ <<<<correct

2. Relevant equations

for part b: 960*(20/60) = 320

whys it wrong?!

Last edited: Mar 17, 2008
2. Mar 18, 2008

### Staff: Mentor

One Watt = one Joule per second. You need to multiply the power (960 W) by the time in seconds (not hours).