Suppose you spend 30.0 minutes on a stair-climbing machine, climbing at a rate of 75 steps per minute, with each step 8.00 inches high. If you weigh 150 lb and the machine reports that 690 kcal have been burned at the end of the workout, what efficiency is the machine using in obtaining this result?
I know the answer to the first part is
10.4%
but i'm not sure how to find this second part...
If your actual efficiency is 0.20, how many kcal did you really burn?
___________kcal
How did you get the first part?
To have an efficiency of 20% and to have done the same amount of work, you need to have burned fewer kcal, by a ratio of 10.4/20. That makes 359 kcal
To find the number of calories you actually burned, you can calculate it using the efficiency of the machine. The formula for calculating calories burned is:
Calories burned = Efficiency * Machine calories
Given that the efficiency is 0.20 and the machine reports 690 kcal, we can substitute the values into the formula:
Calories burned = 0.20 * 690 kcal
Calories burned = 138 kcal
Therefore, you actually burned 138 kcal.
To find the answer to the second part of the question, we need to use the given information that your actual efficiency is 0.20. Efficiency is defined as the ratio of useful output to the input, so in this case, it represents the ratio of actual calories burned to the reported calories burned.
The given information states that the machine reported 690 kcal burned. To find the actual calories burned, we multiply the reported calories by the actual efficiency:
Actual calories burned = Reported calories burned * Actual efficiency
Actual calories burned = 690 kcal * 0.20
To calculate the answer, we simply perform the multiplication:
Actual calories burned = 138 kcal
Therefore, you actually burned 138 kcal during the workout.