Respuesta :
ANSWER
[tex]612,500J[/tex]EXPLANATION
The efficiency in converting chemical energy to mechanical energy is 18%. This implies that 0.18 of chemical energy is converted to mechanical energy.
Let the amount of chemical energy be x.
Let the amount of mechanical energy be y.
Hence:
[tex]0.18x=y[/tex]The mechanical energy required to lift a 15 kg mass 1.5 m is the potential energy i.e.:
[tex]PE=mgh[/tex]where m = mass; g = acceleration due to gravity; h = height
Therefore, we have that:
[tex]\begin{gathered} PE=15\cdot9.8\cdot1.5 \\ PE=220.5J \end{gathered}[/tex]If the activity is repeated 500 times, the energy required is:
[tex]\begin{gathered} y=220.5\cdot500 \\ \Rightarrow y=110,250J \end{gathered}[/tex]Recall that:
[tex]0.18x=y[/tex]This implies that the chemical energy that the student must consume is:
[tex]\begin{gathered} x=\frac{y}{0.18} \\ x=\frac{110250}{0.18} \\ x=612,500J \end{gathered}[/tex]