1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Power Equation?

  1. Oct 16, 2012 #1
    Power Equation??

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

    An ice cube is placed in a microwave oven. Suppose the oven delivers 135 W of power to the ice cube and that it takes 33200 Joules to melt it. How long does it take for the ice cube to melt?

    2. Relevant equations

    P = W / T

    3. The attempt at a solution

    Ok so I know the answer but this is confusing me... A unit of Power is J/second. So if we rearrange the equation and solve for T in minutes it would be.

    T = W / P,

    T = 135 / 33200 which doesn't give us the right equation to solve it...

    Instead it would be 33200 / 135 / 60 = 4.1 minutes, But why when I rearrange the equation doesn't it make sense?
     
    Last edited: Oct 16, 2012
  2. jcsd
  3. Oct 16, 2012 #2

    lewando

    User Avatar
    Gold Member

    Re: Power Equation??

    33200 of what units? Badly stated question. "135 of power"?

    P = W/T ? What do you think P and W represent?
     
  4. Oct 16, 2012 #3
    Re: Power Equation??

    Power = Watts / Time, Fixed my typo up above.

    Ugh nvm I just went full retard. I read the question wrong. Ty anyway!
     
  5. Oct 16, 2012 #4

    lewando

    User Avatar
    Gold Member

    Re: Power Equation??

    Use power = work (or energy) / time. Power has units of Watts.
     
  6. Oct 16, 2012 #5
    Re: Power Equation??

    Yea that's what confused me... I mixed up watts and work. Ty!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Power Equation?
  1. Power equations (Replies: 4)

Loading...