Question

The food calorie, equal to 4186 JJ, is a measure of how much energy is released when food is metabolized by the body. A certain brand of fruit-and-cereal bar contains 160 food calories per bar.

A.If a 66.0 kgkg hiker eats one of these bars, how high a mountain must he climb to "work off" the calories, assuming that all the food energy goes only into increasing gravitational potential energy?

B.If, as is typical, only 20.0 %% of the food calories go into mechanical energy, what would be the answer to part (a)? (Note: In this and all other problems, we are assuming that 100 % of the food calories that are eaten are absorbed and used by the body. This is actually not true. A person's "metabolic efficiency" is the percentage of calories eaten that are actually used; the rest are eliminated by the body. Metabolic efficiency varies considerably from person to person.)

Answer 1

A.

Energy gained from food is

E = 160x4186J

= 669760 J

Energy used up in climbing is equal to the increase in the potential energy.

U = mgh

Therefore from,U = E

height of the mountain,

       h = E/mg

=669760/(63x9.81)

= 1083.70 m

B.

When only 23% of food energy isavailable.

Then, E x 0.20 = mgh'

          Height, h' = 669760x0.20/(63x9.81)

                         = 216.74 m

Dear student,

Please “LIKE” the solution If you have any doubt please ask me in the comment before rate I will clear your doubt as soon as possible by the comments.....

Your LIKES are very important for me so please LIKE….