Question

Ray creates an energy transfer diagram for a hair dryer. However, the diagram contains an error that could be corrected in several different ways.

An illustration of a very wide arrow with a hair dryer at the tail labeled electrical energy 750 J. The arrow breaks into a 3 arrows a medium arrow going straight labeled kinetic energy 125 J and a much larger arrow curling away labeled thermal energy 550 J and the smallest curling away labeled sound energy 150 J.

Which of these changes would make the diagram error-free? Check all that apply.

reducing the amount of thermal energy to 475 J
increasing the amount of electrical energy to 825 J
increasing the amount of sound energy to 225 J
reducing the amount of kinetic energy to 50 J
reducing the amount of electrical energy to 675 J

Answer 1

The outputs must add up to the input (750 J). Current outputs sum to 125 + 550 + 150 = 825 J, so the diagram is inconsistent.

Check each change:
- Reduce thermal to 475 J: outputs = 125 + 475 + 150 = 750 J → fixes it. (Yes)
- Increase electrical to 825 J: input = 825 J and outputs = 825 J → fixes it. (Yes)
- Increase sound to 225 J: outputs = 125 + 550 + 225 = 900 J → still wrong. (No)
- Reduce kinetic to 50 J: outputs = 50 + 550 + 150 = 750 J → fixes it. (Yes)
- Reduce electrical to 675 J: input = 675 J vs outputs 825 J → wrong. (No)

So the correct choices are: reducing thermal to 475 J; increasing electrical to 825 J; reducing kinetic to 50 J.