Question

Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as. Metabolizing 1 g of fat can release. A student decides to try to lose weight by exercising. He plans to run up and down the stairs in a football stadium as fast as he can and as many times as necessary. To evaluate the program, suppose he runs up a flight of 80 steps, each high, in. For simplicity, ignore the energy he uses in coming down (which is small). Assume a typical efficiency for human muscles is 20.0%. This statement means that when your body converts from metabolizing fat, 20 J goes into doing mechanical work (here, climbing stairs). The remainder goes into extra internal energy. Assume the student’s mass is. (a) How many times must the student run the flight of stairs to lose of fat? (b) What is his average power output, in watts and in horsepower, as he runs up the stairs? (c) Is this activity in itself a practical way to lose weight?

Short answer

(a) The no. of times must the student must run the flight of stairs to lose 1.00 Kg of fat is. n=854

Step-by-step solution

Step-by-step-solutionStep 1: calculation

Power is described as the amount of work done in unit time.

$P=\frac{w}{△t}$

Where,

P= Power

W=Work done

$△t$=Change in time in second

Energy conservation can be represented as-

$△k+△U+△{\mathrm{E}}_{int}=0$

Where,

$△K=$Change in kinetic energy

$△U=$Change in potential energy

$△E_{int}=$Change in internal energy

Given Data

$$\begin{gathered} 1\mathrm{Kcl}=4186\mathrm{J} \\ 1\mathrm{g}\mathrm{releases}9.0\mathrm{Kcl} \\ \mathrm{number}\mathrm{of}\mathrm{steps}:80 \\ \mathrm{height}\mathrm{of}\mathrm{each}\mathrm{step}:1.5\mathrm{m} \\ \mathrm{time}\mathrm{taken}:65\mathrm{s} \\ \mathrm{student}’\mathrm{s}\mathrm{mass}:75\mathrm{kg} \\ \mathrm{efficiency}:20\% \end{gathered}$$

 Calculation Part (a)

Burning 1 kg of fat releases energy

The mechanical energy output is

here n is the number times the student should run up and down. Then

The number of times the student should run the flight of stairs is 854