Answer:
T = 76.39°C
Explanation:
given,
coffee cup temperature = 95°C
Room temperature= 20°C
expression
temperature at t = 0
T(0) = 95°C
temperature after half hour of cooling
t = 30 minutes
T(30) = 61.16° C
average of first half hour will be equal to
![T = \dfrac{1}{30}[(20t - \dfrac{75 e^{\dfrac{-t}{50}}}{\dfrac{1}{50}})]_0^30](https://tex.z-dn.net/?f=T%20%3D%20%5Cdfrac%7B1%7D%7B30%7D%5B%2820t%20-%20%5Cdfrac%7B75%20e%5E%7B%5Cdfrac%7B-t%7D%7B50%7D%7D%7D%7B%5Cdfrac%7B1%7D%7B50%7D%7D%29%5D_0%5E30)
![T = \dfrac{1}{30}[(20t - 3750e^{\dfrac{-t}{50}}]_0^30](https://tex.z-dn.net/?f=T%20%3D%20%5Cdfrac%7B1%7D%7B30%7D%5B%2820t%20-%203750e%5E%7B%5Cdfrac%7B-t%7D%7B50%7D%7D%5D_0%5E30)
![T = \dfrac{1}{30}[(20\times 30 - 3750 e^{\dfrac{-30}{50}} + 3750]](https://tex.z-dn.net/?f=T%20%3D%20%5Cdfrac%7B1%7D%7B30%7D%5B%2820%5Ctimes%2030%20-%203750%20e%5E%7B%5Cdfrac%7B-30%7D%7B50%7D%7D%20%2B%203750%5D)
![T = \dfrac{1}{30}[600 - 2058.04 + 3750]](https://tex.z-dn.net/?f=T%20%3D%20%5Cdfrac%7B1%7D%7B30%7D%5B600%20-%202058.04%20%2B%203750%5D)
T = 76.39°C
The work done is given by 742.5 J while the coefficient of kinetic friction between the block and the surface is 0.46.
<h3>What is the work done?</h3>
The work done is given by the use of the formula;
W = F * x
Where;
F = force applied
x = distance covered
W = 150 N * 4.95 m = 742.5 J
Now;
The coefficient of kinetic friction is given by;
μ = F/mg
μ = 150/ 33 * 9.8
μ = 0.46
Learn more about work done:brainly.com/question/13662169
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Answer:
Polished surfaces reduce heat loss
Answer: yeah it is reflection
