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

[lettertwelve]

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

Homework Statement

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

Homework Equations

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

whys it wrong?!

 

[Doc Al]

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

 

[Moetasim]

It seems that you have calculated the power correctly in part (a), but for part (b), you have used the wrong equation. To calculate the energy produced, you need to use the formula E = Pt, where E is the energy in joules, P is the power in watts, and t is the time in seconds. Since the time given in the problem is in minutes, you will need to convert it to seconds before plugging it into the equation. This will give you the correct answer for part (b). Keep in mind that the unit for energy is joules, not watts.

Also, for part (c), you have correctly calculated the cost, but the unit should be in dollars, not cents. So the correct answer would be $0.0032. I hope this helps you understand the problem better and how to approach it in the future. Make sure to always double check your units and equations to ensure accuracy in your calculations. Good luck!