S.O.S!!! In terms of saving energy, bicycling and walking are far more efficient means of transportation than is travel by automobile. For example, when riding at 15.0 mi/h, a cyclist uses food energy at a rate of about 400 kcal/h above what he would use if he were merely sitting still(In exercise physiology, power is often measured in kcal/h rather than in watts. Here, 1 kcal = 1 nutritionist's Calorie = 4,186 J.) Walking at 3.15 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 1.30 108 J/gal.

(a) Find the fuel economy in equivalent miles per gallon for a person walking? mpg

I keep getting 1.4e16 mpg
And it is WRONG???? why?

(b) Find the fuel economy in equivalent miles per gallon for a person bicycling? mpg
cant do without A i think

To find the fuel economy in equivalent miles per gallon for a person walking, we need to compare the energy consumption of walking to that of a car.

First, let's convert the energy consumption of walking from kcal/h to J/h by using the conversion factor: 1 kcal = 4,186 J.

Walking at 3.15 mi/h requires about 220 kcal/h, so the energy consumption in J/h is:

220 kcal/h * 4,186 J/kcal = 920,120 J/h.

Now let's find the fuel economy in equivalent miles per gallon by comparing the energy consumption of walking to the energy yield of gasoline.

Gasoline yields about 1.30 * 108 J/gal.

To calculate the fuel economy, we can divide the energy yield of gasoline (in J) by the energy consumption of walking (in J/h):

Fuel economy = (Energy yield of gasoline) / (Energy consumption of walking)

Fuel economy = (1.30 * 108 J/gal) / (920,120 J/h).

Now, we need to convert the units to miles per gallon (mpg).

To do this, we need to know the conversion factor for miles to meters. Let's assume 1 mile = 1609 meters.

Now, let's convert the units:

Fuel economy = (1.30 * 108 J/gal) / (920,120 J/h)
= (1.30 * 108 J/gal) / (920,120 J/3600 s) [since 1 hour = 3600 seconds]
≈ (1.30 * 108 J/gal) / (920,120 J/s) [approximating 3600 s to 1 s]

Now, we can convert J/s to J/mile:

1 J/s = 1 watt (W), and 1 W = 1 J/s / 1 meter (m) = 1 J/m.

Fuel economy ≈ (1.30 * 108 J/gal) / (920,120 J/mile)

To convert J/mile to J/gallon, we need to convert miles to gallons. Let's assume 1 gallon = 3.78541 liters.

Now, let's convert the units:

Fuel economy ≈ (1.30 * 108 J/gal) / (920,120 J/mile)
≈ (1.30 * 108 J/gal) / (4,186 J/kcal * 220 kcal/1.609 mi) [using the conversion factor of miles to kcal]
≈ (1.30 * 108) / (4,186 * 220 / 1.609) [canceling out the units]

Calculating this, we get approximately:

Fuel economy ≈ 1.44 * 10^(-8) J/gal.

Therefore, the fuel economy in equivalent miles per gallon for a person walking is approximately 1.44 * 10^(-8) mpg.

In summary, the fuel economy in equivalent miles per gallon for a person walking is 1.44 * 10^(-8) mpg.

As for the fuel economy in equivalent miles per gallon for a person bicycling (part b), we need the result of part a. If you can provide the correct answer for part a, we can proceed with part b calculation.