1)

(a)

What is the efficiency of an out-of-condition professor who does 2.10 10⁵ J of useful work while metabolizing 490 kcal of food energy? (Enter your answer as a percentage. Enter a number.) %

(b)

How many food calories (in kcal) would a well-conditioned athlete metabolize in doing the same work with an efficiency of 15%? (Enter a number.) kcal

2)

(a) Calculate the force (in N) the woman in the gure below exerts to do a push-up at constant speed, taking all data to be known to three digits. (You may need to use torque methods from a later chapter.) m=59kg (b) How much work (in J) does she do if her center of mass rises 0.260 m? |:|J (c) What IS her useful power output (in W) W she does 27 push-ups in 1 mm? {Should work done Iowermg her body be included? See the discusslon of useful work in Work, Energy, and Power in Humans.) |:|W