Question

For saving energy, bicycling and walking are far more efficient means of transportation than is travel by automobile. For example, when riding at 12.5 mi/h, a cyclist uses food energy at a rate of about 360 kcal/h above what he would use if merely sitting still. (In exercise physiology, power is often measured in kcal/h rather than in watts. Here 1 kcal = 1 nutritionist's Calorie = 4186 J). Walking at 3.20 mi/h requires about 220 kcal/h. It is interesting to compare these values with the energy consumption required for travel by car. Gasoline yields about 1.30.
A) Find the fuel economy in equivalent miles per gallon for a person walking.
B) Find the fuel economy in equivalent miles per gallon for a person bicycling.

Answer 1

Answer:

a. 451.72 mi/ga

b. 1078.33 mi/ga

Explanation:

The computation is shown below:

a. The fuel economy for a person walking is

Given that

Walking at 3.20 mi/h requires about 220 kcal/h so it is equal to

$= 220 \times 4186$

= 920920 j/hr

Now

$= \frac{mi}{j}$

$= \frac{3.2}{920920}$

So,

$= \frac{mi}{ga}$

$= \frac{3.2}{920920}\times 1.3 \times 100000000$

= 451.72 mi/ga

b. Now

Bicycling 12.5 mi/h requires about 360 kcal/h  energy so it is equal to

$= 360 \times 4186$

= 1506960 j/hr

So,

$= \frac{mi}{j}$

$= \frac{12.5}{1506960}$

Now

$= \frac{mi}{ga}$

$= \frac{12.5}{1506960} \times 1.3 \times 100000000$

= 1078.33 mi/ga

We simply applied the above formula