In: Physics
Estimate the cost of routine use of a 2.50 kW handheld hair dryer for 1 year (52 weeks). Assume that a person uses the hair dryer on average for 18 minutes each day, 4 times per week.
A person uses the hair dryer for 18 min (0.30 h) at a time, 4 times a week on average. That means that in 52 weeks he/she uses it an average of 208 times.
Step 1
Given data:
\( P = \rm 2.50\,kW \\ \)
\( N = 4\times 52 = 208\ \text{times per year}\ \)
\( t = \rm 0.30\,h \times 208 = 62.4\,h \ \)
Step 2
\( {\rm Energy} = P\times t = \rm (2.50\,kW)(62.4\,h) = 156\,kWh \ \)
Step 3
If we assume that the cost of electricity is about $0.150 per kWh, then the estimated cost (C) of the electricity consumed by the hair dryer for one year is
\( C = \rm {\rm Energy}( $ 0.150/ kWh) = (156\, kWh)( $0.150/ kWh) = \boxed{ $23.4} \)
The annual cost of using a hair dryer is about $23.4.