A hair dryer that has a power rating of 1000 W uses 1.75 kW-h in one week. For how many hours (or minutes) is the hair dryer used daily on average?
Power = The Rate of Doing Work, that is:- Work Done/The time taken
Time taken = Work Done/ Power rating of electrical appliance.
Therefore, time for which hair drier was ‘on’ is given by:- 1.75kW-h / 1000 kW = 1.75hr.
1.75 hrs = 60 +(0.75 x 60) mins = 60 +45 = 105 mins. This is the time the hair drier is on per week.
The average daily consumption will be 105/7= 15 mins
Ans: 15 mins per day.
1000 Watts = 1 kw
In order to use 1.75kw-h the hairdryer would need to be used for 1.75 hours i.e 1 3/4 hours or
1hr 45mins.
hope this helps
References :
Power = The Rate of Doing Work, that is:- Work Done/The time taken
Time taken = Work Done/ Power rating of electrical appliance.
Therefore, time for which hair drier was ‘on’ is given by:- 1.75kW-h / 1000 kW = 1.75hr.
1.75 hrs = 60 +(0.75 x 60) mins = 60 +45 = 105 mins. This is the time the hair drier is on per week.
The average daily consumption will be 105/7= 15 mins
Ans: 15 mins per day.
References :
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