MECHANICAL EFFICIENCY

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Mechanical Efficiency Formula and Example
A 400N TV is needed to be moved up 5 metres, if a person moves the TV up a 10 metre ramp with the force of 250N what is the mechanical efficiency? The work input is 2500J and the work output is 2000J. 2000J divided by 2500J is 0.8. 0.8 times 100% is 80% therefore the mechanical efficiency is 80%.
Wo = F x d
Wo = 400N x 5m
Wo = 2000J

Wi = F x d
W
i = 250N x 10m
W
i = 2500J

ME = (Wo/Wi) x 100%
ME = (2000J/2500J) x 100%
ME = 0.8 x 100%
ME = 80%