# Physics - calculating energy costsWatch

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#1
Hello all I am confused as to how I should answer questions on energy costs, any help would be appreciated.

If one unit costs 12 pence calculate the following

'The TV set has a power rating o 800W. How much does it cost to run the TV for 2 hours?'

I'm unsure of what formula to use?
and
'A kettle has a power rating of 21kW, how much does it cost to run the kettle for 5 minutes?

Physics confuses me aha
Cheers
0
6 years ago
#2
(Original post by undiscovered_)
Hello all I am confused as to how I should answer questions on energy costs, any help would be appreciated.

If one unit costs 12 pence calculate the following

'The TV set has a power rating o 800W. How much does it cost to run the TV for 2 hours?'

I'm unsure of what formula to use?
and
'A kettle has a power rating of 21kW, how much does it cost to run the kettle for 5 minutes?

Physics confuses me aha
Cheers
For the TV:
That unit cost will be 12 pence per kilowatt hour (12p/kWh)

therefore: 800W = 0.8kW x 2 hours = 1.6 kWh

cost will be: 12p/kWh x 1.6kWh = 19.2 pence.

For the kettle:
5 minutes = one twelfth of an hour = 0.08333 hours.

21kW x 0.08333 = 1.75kWh

cost will be: 12p/kWh x 1.75kWh = 21 pence.
0
6 years ago
#3
(Original post by M e m p h i s)
*****
We understand your wish to help the poster, but please note the forum guidelines
http://www.thestudentroom.co.uk/wiki...ring_questions
which ask that you don't post complete solutions to problems.
Just the first step or two is sufficient to help the poster answer the question for him or herself. Or for a short answer like these, a hint or prod in the right direction will be enough to start with.
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