Question

Nora's hair dryer is 64% efficient. If 1000 J of energy is supplied to the hair dryer, how much energy will it transfer usefully to Nora's hair?

Answer 1

The hair dryer will transfer 640J of energy usefully to Nora’s hair.

Step-by-step explanation:

Efficiency = output/input × 100%

Data

Efficiency = 64%

Energy input = 1000J

Energy output = ?

Efficiency = Energy output/Energy input × 100%

64% = Energy output /1000J × 100%

Divide both sides by 100%

0.64 = Energy output/1000J

Energy output = 0.64 × 1000J

Efficiency output = 640J

Therefore the hair dryer will transfer 640J of energy usefully to Nora’s hair.