Calculate net efficiency,given the following: Resting VO₂ = 0.25 liters per minute
Exercise VO₂= 1.50 liters per minute
Work rate = 100 watts (W) or 612 kilopond meters per minute
1 watt = 1 joule per second
1 kcal = 4186 joules
1 liter VO₂= 5 kcal or 20,930 joules

Question

Quizplus · Accepted Answer

First, we need to calculate the amount of energy expended during exercise: Energy = work rate x time Since work rate is given in watts, and time is not given, we cannot yet calculate absolute energy expenditure. However, we can use the VO₂ values to determine relative energy expenditure, since we know that 1 liter of VO₂ = 5 kcal or 20,930 joules. Resting energy expenditure: 0.25 L/min x 5 kcal/L = 1.25 kcal/min or 5230 joules/min Exercise energy expenditure: 1.50 L/min x 5 kcal/L = 7.50 kcal/min or 31,395 joules/min Net efficiency is calculated using the formula: Net Efficiency = Work output / Energy input x 100% The work output is given in units of kilopond meters per minute, so we need to convert to joules per minute to match our units of energy input. 1 kilopond-meter = 9.80665 joules Therefore, 612 kilopond meters/min x 9.80665 J/kpm = 6004.51 joules/min Now we can calculate net efficiency: Net Efficiency = 6004.51 / (5230 + 31395) x 100% Net Efficiency ≈ 22.8% The closest answer choice is C, approximately 23%.

Calculate Net Efficiency,given the Following: Resting VO2 = 0

Calculate Net Efficiency,given the Following: Resting VO₂ = 0