A model for the temperature in a room, in degrees Celsius, is given by
where
- Express the derivative
as a hybrid function. (2 marks)
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- Find the average rate of change in temperature predicted by the model between
and . - Give your answer in degrees Celsius per hour. (1 mark)
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- Another model for the temperature in the room is given by
. - i. Find the derivative
. (1 mark)
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- ii. Find the value of
for which . - Give your answer correct to three decimal places. (1 mark)
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- Find the time
when the temperatures predicted by the models and are equal. - Give your answer correct to two decimal places. (1 mark)
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- Find the time
when the difference between the temperatures predicted by the two models is the greatest. - Give your answer correct to two decimal places. (1 mark)
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- The amount of power, in kilowatts, used by the heater
hours after it is switched on, can be modelled by the continuous function , whose graph is shown below.
The amount of energy used by the heater, in kilowatt hours, can be estimated by evaluating the area between the graph of
- i. Given that
is continuous for , show that . (1 mark)
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- ii. Find how long it takes, after the heater is switched on, until the heater has used 0.5 kilowatt hours of energy.
- Give your answer in hours. (1 mark)
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- iii. Find how long it takes, after the heater is switched on, until the heater has used 1 kilowatt hour of energy.
- Give your answer in hours, correct to two decimal places. (2 marks)
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