I searched again and calculated but it doesn't seem like I'm getting it right. Can someone use the G-R-A-S-P formula and give me an answer to this question?

a cd player has a power rating of 800 watts and runs for 4.5 hours. How much energy is being put into it?
It has an output of 1500 j, how efficient is the cd player?

It's all calculating output and input and efficiency. Thanks.
yea I can't get the formula though, I tried for quite a bit. If someone is answering this, could you explain a little on it too?
Quote by Shib
isn't there a formula sheet you get?


t / wats * output?

that says t wats.

sorry for my useless post.
I have no idea what GRASP is, but watts = joules/second.

So just convert hours to seconds and multiply by the energy consumption to find out how much energy is used.

In other words, E = P*t, where E is energy in joules, P is power in watts and t is time in seconds.

Then divide output energy by input energy to find the efficiency.

Also, there is a science thread somewhere around here.
Last edited by Ipster at Jan 8, 2007,