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 would have been his performance if the whole exercise had taken 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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