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A kettle has a 55% energy efficiency. The input energy for the kettle is 378,000 J per boil. Calculate the amount of energy dissipated in 5 boils.

Energy used for one boil = (3.78 x 10 5 / 100) x 55Energy used for one boil = 2.079 x 10 5 J Energy lost per boil = 3.78 x 10 5 -2.079 x 10 5 Energy lost per boil = 1.701 x 10 5 Energy lost per 5 boils = (1....
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Answered by Ryan A. • Physics tutor
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Explain what is meant by the term placebo, and how a placebo would be utilised in a clinical trial of a novel pain relief medication

A placebo is a control method to account for perceived effects of taking a medication. This is because patients often report that they feel a difference from taking a medication, irrespective of whether it h...
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Answered by Ryan A. • Biology tutor
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Find the 1st derivative of y = x^2 + 7x +3 and hence find the curves minima.

Firstly, we differentiate y = x 2 +7x+3 . This gives dy/dx = 2x+7.The minimum value occurs when dy/dx = 0. So find x and y when dy/dx=0. 2x+7=0 implies x= -3.5, which from the first equation means y = (-3.5)...
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Answered by Connor W. • Maths tutor
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How do I respond to a Shakespeare extract?

Read the question carefully. Don't be afraid to underline keywords in the question. Often exam papers will ask you to write about themes like love, confusion, war and greed. If you see a big scary-sounding n...
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Answered by James C. • English tutor
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Explain the reasons for the changes in reactivity of Phenol, Benzene and MethylBenzene

The changes in reactivity are due to the electron donating/withdrawing properties of the substituted groups. For example the OH group in Phenol is electron donating. This means the electron density of the de...
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Answered by Adam D. • Chemistry tutor
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