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PSYCHO15rus [73]
3 years ago
9

An electronic device dissipating 25 W has a mass of 20 g and a specific heat of 850 J/kg·0K. The device is lightly used, and it

is on for 5 min and then off for several hours, during which it cools to the ambient temperature of 250C. Let the mass of heat sink vary from 0 to 1 kg. Plot the maximum temperature against the mass of heat sink, and discuss the results. U

Engineering
1 answer:
7nadin3 [17]3 years ago
7 0

Answer:

Explanation:

FIrst let c be the specific heat, now we need the heat that the device is able to provide:

so it is turned on for 5 minutes (300 seconds) with 25 Watts

Q = Power*time = (25)*(300) = 7500J

Now heat is equal to the change in internal energy, where we will use the remaining terms.

Now we continue

Q = \Delta U = M*C(\Delta T)

where \Delta T is the change of temperature ( \Delta T = T_{final} - T_{initial} )

now Q = \Delta U = M*C*(T_{final} - T_{initial})

We solve T_{final} = \frac{Q}{M*C} +T_{initial}

now we just plot it for different values of M using any software..

please find attached the plot of the temperature.

The result indicates that as the mass increases it is harder for the system to reach higher final temperatures.

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