The human heart is a powerful and reliable pump. Each day it takes in and discharges about 7500 L of blood. Suppose the work done is equal to that required for lifting this blood a height of 1.292m and that the blood density is that of water, 1.00x10^3 kg/m^3. a) What work in joules is done by the heart in a day? b) What is its power output in watts? c) At a food conversion efficiency of 7.44%, how many food calories ( one food calorie=4190 joules) must be taken from the daily diet for the heart?