Energy of locomotion. On flat ground, a 70 kg person requires about 300 W of
metabolic power to walk at a steady pace of 5.0 km/h. Using the same metabolic
power output, that person can bicycle over the same ground at 15 km/h. (10 pts.)
(a) Based on the given data, how does the energy used in biking 1 km compare with
that used in walking 1 km? Biking takes (I) 1/3 of the energy of walking the
same distance; (II) the same energy as walking the same distance; (III) 3 times
the energy of walking the same distance; (IV) 9 times the energy of walking the
same distance.
(b) A 70 kg person walks at a steady pace of 5.0 km/h on a treadmill at a 5.0% grade.
(That is, the vertical distance covered is 5.0% of the horizontal distance covered.)
If we assume the metabolic power required is equal to that required for walking
on a flat surface plus the rate of doing work for the vertical climb, how much
power is required? (I) 300 W; (II) 315 W; (III) 350 W ; (IV) 370 W.
(c) How many times greater is the kinetic energy of the person when biking than
when walking? Ignore the mass of the bike. (I) 1.7; (II) 3; (III) 6; (IV) 9.