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.

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

= 920920 j/hr

Now

So,

= 451.72 mi/ga

b. Now

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

= 1506960 j/hr

So,

Now

= 1078.33 mi/ga

We simply applied the above formula

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

answer: the potential energy decreases from 379 j to 243 j

explanation:

for the law of conservation of energy, the total energy in a system must be conserved. the total energy of the system is given by the sum of kinetic (k) and potential (u) energy:

e = k + u

the total energy is e=675 j, and this does not change.

initially, the kinetic energy is k=296 j, so the potential energy is

at the end, the kinetic energy is k=432 j, so the potential energy is

so, we see that the potential energy has decreased from 379 j to 243 j.