Homework Help: Integrated Physics and Science

Posted by Nella on Monday, January 10, 2011 at 11:07am.

A crowbar is used as a lever. The effort force of 40 newtons moves 3 meters. The resistance force of 54 newtons moves 2 meters. What is the efficiency of the lever?

A) 100% because energy must be conserved
B) 90%
C) 25%
D) 18%

i need help. i don't know how to figure this one out

Integrated Physics and Science - drwls, Monday, January 10, 2011 at 11:53am
Output work = 108 J.
Input work = 120 J

Efficiency = 108/120 = 9/10 = 90%

(Energy can be converted to heat in friction at the fulcrum, or useless potential energy distorting the crowbar)
Integrated Physics and Science - Nella, Tuesday, January 11, 2011 at 10:57am
oh okay. i get it now. Thank you very much
Integrated Physics and Science - Helen, Tuesday, January 11, 2011 at 5:28pm
Southeast Academy Switched-on online?
Integrated Physics and Science - Anonymous, Tuesday, November 15, 2011 at 4:37pm
What is the unit for IMA?
Integrated Physics and Science - phillip, Thursday, June 28, 2012 at 1:17pm
IMA is unitless
Integrated Physics and Science - billy, Monday, November 26, 2012 at 8:42am
yes
Integrated Physics and Science - Anonymous, Tuesday, March 19, 2013 at 9:27am
b

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