CK-12 Physical Science Concepts - For Middle School

(Marvins-Underground-K-12) #1

4.40. Efficiency http://www.ck12.org



  • You can calculate the efficiency of a machine with this equation: Efficiency=Output workInput work×100%


Vocabulary



  • efficiency: Measure of how well a machine reduces friction; calculated as the percent of input work that
    becomes output work.


Explore More


At the following URL, review efficiency and how to calculate it. Then do the problems at the bottom of the Web
page. Check the correct answers and the explanations for them.


http://equalrightsforall.net/classical_mechanics/energy/023_Machines.html


Review



  1. Why is the output work of a machine always less than the input work done on the machine?

  2. What is the efficiency of a machine?

  3. If a machine requires an input of 5000 joules of work to put out 4000 joules of work, what is the machine’s
    efficiency?

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