Calculating Energy Usage of a Hair Dryer

In summary, the problem asks for the amount of electrical energy used by a 1650-W hair dryer in 10 minutes, which can be found using the equation w=Pt. The correct answer is 9.9 x 10^5 Joules. To calculate the contribution to the electrical bill, the 4.5 hours of operation must be converted to minutes to match the units used in part (a).
  • #1
aquamarine08
23
0
[SOLVED] Power problem!

Homework Statement



(a) How many joules of electrical energy are used by a 1650-W hair dryer in 10 min? (b) If the dryer is operated a total of 4.5 h during one month, how much will this contribute to the electrical bill if the billing rate is 12 cents/kWh?

Homework Equations



P=[tex]\frac{w}{t}[/tex] --> w=Pt

The Attempt at a Solution



(a) w=Pt -> (1650)(10)= 16500 J

I figured since the answer was supposed to be in Joules, I would use the equation w=Pt to figure out the amount but I ended up getting the wrong answer. The correct answer is 9.9 x [tex]10^{5}[/tex].

(b) Since I didn't get the right answer for (a) I knew my answer wouldn't be right here either. I don't really know how to solve this question either but I figured I should convert the 4.5 h into minutes so it matches the amount for part (a)..so I got 190 minutes, and that's pretty much it.

Please help, we didn't get any notes to refer to for this homework and it is our first day learning about Power. :confused:
Thanks so much.:smile:
 
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  • #2
(a) w=Pt -> (1650)(10)= 16500 J

For part (a): since 1 Watt = 1 Joule/second, you need to change the 10 minutes into seconds to keep your units consistent.
 
  • #3
ok thanks...i got part a! now I am just workin on b...
 

1. How do I calculate the energy usage of my hair dryer?

To calculate the energy usage of your hair dryer, you will need to know the wattage of your hair dryer and the amount of time it is used. Multiply the wattage by the number of hours used to get the watt-hours (Wh) and then divide by 1000 to get the kilowatt-hours (kWh).

2. What is the average wattage of a hair dryer?

The average wattage of a hair dryer is around 1200 watts. However, this can vary depending on the brand and model of the hair dryer.

3. How long should I use my hair dryer to save energy?

The best way to save energy while using a hair dryer is to limit the amount of time it is used. Generally, it is recommended to use a hair dryer for no more than 10-15 minutes at a time to conserve energy.

4. Can using a hair dryer on a lower heat setting save energy?

Yes, using a hair dryer on a lower heat setting can save energy. The higher the heat setting, the more energy the hair dryer will consume. Using a lower heat setting will also be gentler on your hair.

5. Is it more energy efficient to air dry my hair instead of using a hair dryer?

Air drying your hair is more energy efficient than using a hair dryer. However, air drying may take longer and may not be practical for everyone. If you need to use a hair dryer, try to limit the amount of time it is used and use a lower heat setting to save energy.

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