Question

Normally the rate at which you expend energy during a brisk walk is 3.6 Calories per minute. (A Calorie is the common unit of food energy, equal to 4184.1 J.) How long do you have to walk to produce the same amount of energy as a 150 W lightbulb that is lit for 5.8 hours?

Answer 1

3.5 hour

Explanation:

During a brisk walk, rate at which energy is expended is P(expend) = 3.6 calories per min

1 calorie = 4184.1 J

Energy produced by bulb is P(bulb) = 150W

time = 5.8 hrs

Convvert 5.8 hrs to secs. we have

t = 5.8*3600

t= 20880 secs

Power = Energy/time

150 = energy / 20880

Energy = 150 * 20880

= 3132000J

Convert the rate at which cv h energy is expended into joules per second, we have

(3.6 * 4184.1)/60

P(expend) = 251J/s

= 251W

Recall that P = E/t

t = E/p

t = 3132000/251

t = 12478 secs

Convert secs to hour

t = 12478/ 3600

t= 3.5 hours

The time requtied to produce the s\me amount of energy as 150W bulb that lights up 5..8hrs is t = 3.5 hrs