Performance 7737

Zdenek, weighing 54 kg, made 15 push-ups on the crossbar. The height he reached was about 40 cm. What kind of work did he do? What was his performance if the whole exercise took him a minute and a half?

Correct answer:

W =  3240 J
P =  36 W

Step-by-step explanation:

$$\begin{gathered} m=54\text{kg} \\ h=40\text{cm}\to \text{m}=40:100\text{m}=0.4\text{m} \\ n=15 \\ g=10{\text{m/s}}^2 \\ W=m\cdot g\cdot h\cdot n=54\cdot 10\cdot 0.4\cdot 15=3240\text{J} \end{gathered}$$

$$\begin{gathered} t=1.5\text{min}\to \text{s}=1.5\cdot 60\text{s}=90\text{s} \\ P=W/t=3240/90=36\text{W} \end{gathered}$$

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