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A 790N person runs up a flight of 40 stairs (.25m for each step) in 20 seconds, and then down 10 steps in 5 seconds. How much total mechanical work is completed? How much total mechanical power is generated? Show all work.

Respuesta :

A person runs up 40 stairs and then come down 10 steps

So total stairs upwards is given as

[tex]N = 40 - 10 = 30[/tex]

now here we will have total height reached

[tex]H = N\times h[/tex]

[tex]H = 30 \times 0.25 = 7.5 m[/tex]

Now total energy used or mechanical work done is

[tex]W = mgH[/tex]

[tex]W = 790 \times 7.5 = 5925 J[/tex]

Now the mechanical power is given as

[tex]P = \frac{W}{t}[/tex]

[tex]P = \frac{5925}{20+ 5} = 237 W[/tex]

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