Answer:
The muscles can perform 320 J of work.
Explanation:
Let the work performed by the muscles be [tex]W_{out}[/tex] J.
Efficiency of a body is given as the ratio of useful work to that of work supplied.
Here, the work provided by the candy bar is, [tex]W_{in}=800\ J[/tex]
Efficiency of the muscles is, [tex]\eta =40\%=0.40[/tex]
Now, we know that,
[tex]\textrm{Efficiency,}\ \eta=\frac{W_{out}}{W_{in}}\\0.40=\frac{W_{out}}{800}\\W_{out}=0.40\times 800=320\ J[/tex]
Therefore, the work performed by the muscles is 320 J.
