littlemiss Posted May 15, 2006 Posted May 15, 2006 If an engine must do 500 joules of work to pull a 10 kg load up to a heaight of 4 meters, what is the efficiency of the engine? I got 8%. Am I correct?
timo Posted May 15, 2006 Posted May 15, 2006 Don´t think so. Perhaps it´s best if you show us how you calculated your result so maybe someone can point out where your error lies.
littlemiss Posted May 15, 2006 Author Posted May 15, 2006 Work done: 10kg*9.8N/kg*4=appx 400J efficience= work done/500 * 100 I don't know what I'm doing wrong.
littlemiss Posted May 15, 2006 Author Posted May 15, 2006 OH! I knew my question looked weird! I completely forgot the 0 in 80%! So, let me rephrase. Am I correct in my answer of 80%?
timo Posted May 15, 2006 Posted May 15, 2006 That look good, yes. The reason I asked you to show your calculation (apart from that it´s always a good idea to do so) was that I assumed you might have forgotten the factor 9.81 m/s².
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