Consider a long plastic rod (rho=1000 kg/m3 Cp=1.040 kJkgK, k=0.3 W/m·K) of diameter 30 mm that is heated uniformly in an oven to Ti and then allowed to convectively cool in ambient air (T[infinity]=25°C, h=8 W/m2·K) for a four minute period. If the minimum temperature of rod cannot be less than 170°C, to what temperature should the rod be heated to? In addition, the maximum-minimum temperature difference within the rod should not exceed 10°C. Is this condition met? Please DO NOT interpolate, use closest values in tables if tables are used.

answer:

the answer is d

explanation:

the equation above shows how temperature f, measured in degrees fahrenheit, relates to a temperature c, measured in degrees celsius. based on the equation, which of the following must be true?

a temperature increase of 1 degree fahrenheit is equivalent to a temperature increase of

5

9

degree celsius.

a temperature increase of 1 degree celsius is equivalent to a temperature increase of 1.8 degrees fahrenheit.

a temperature increase of

5

9

degree fahrenheit is equivalent to a temperature increase of 1 degree celsius.

a) i only

b) ii only

c) iii only

d) i and ii only

answer:

the answer is d

explanation: