The same engineer decides to look into rates of cooling for liquids to experiment with different cooling solutions for servers. She finds that the rate of cooling for one liquid can be modelled by the equation: y = 48 × 0.99t (0 ≤ t ≤ 80) where y is the temperature of the liquid in degrees Celsius and t is the time in minutes. (i) State whether the type of reduction for this model is linear or exponential. Describe how reduction rate differs between linear and exponential functions. (ii) Calculate the temperature when t = 20. [3] (iii) Write down the scale factor and use this to find the percentage decrease in the temperature per minute. (iv) Use the method shown in Subsection 5.2 of Unit 13 to find the time at which the temperature is 30◦ (v) Determine the halving time of the temperature.

The same engineer decides to look into rates of cooling for liquids to experiment with different cooling solutions for servers. She finds that the rate of cooling for one liquid can be modelled by the equation: y = 48 × 0.99t (0 ≤ t ≤ 80) where y is the temperature of the liquid in degrees Celsius and t is the time in minutes. (i) State whether the type of reduction for this model is linear or exponential. Describe how reduction rate differs between linear and exponential functions. (ii) Calculate the temperature when t = 20. [3] (iii) Write down the scale factor and use this to find the percentage decrease in the temperature per minute. (iv) Use the method shown in Subsection 5.2 of Unit 13 to find the time at which the temperature is 30◦ (v) Determine the halving time of the temperature.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter6: Forced Convection Over Exterior Surfaces

Section: Chapter Questions

Problem 6.21P

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