Question

you take an ice-cream out if the freezer, ketp at - 18°C .outside it is 32°C after ine minute the ice cream has warmed to - 8°C what is the temperature if the icecream ofter five miniutes? (ans- 15.6°C)​

Answer 1

Explanation:

Let T be the temperature of the ice cream(in °c) ater T minutes out the freezer. The Newtone's law gives

dt = k(T-32) = -kT + 32

Remebering that k is constant, solving this different equation give a general solution of

T = Ce - Kt +32

since T = -18 when t =0, we obtain -18 = C+32, so C = -50. Since T = -8 when t =1, we have -8 =-50e -k+32, which gives k= loge54 . we obtain

T = -50(45)5+32 = 1952125 = 15.6 °c

Your ice cream has well and truly melted! Note that we have effectively assumed that the Ice cream is a block of a single temperature -- not very realistic.

Answer 2

2. You take an ice-cream out of the freezer, ketp at - 18 deg ° C outside it is 32 °c After one minute the ice creeam has warmed to - 8 deg C what is the temperature of the icecream ofter five minute ( Ans , approx15.6^ C)