Application of differential equations

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A particular isotope of Uranium decays to half of its original amt in 25 days. Find the equation relating the amount present as a function of time and find the percentage remaining after 45 days.



Given - $fracdNdt = KN$



I used separable method to solve it to become - $ N = Ce^kt$



Let original amount be $N_0$ when $t=0$



$N_0 = C $2



Given when $N=0.5N_0$ in 25 days,



$0.5N_0 = N_0 cdot e^25k $



$k = - 0.02773$



Thus the general solution - $ N = Ce^-0.02773 t $



I need to find the particular solution using initial conditions to be able to find the amount remaining after 45 days . But I am stuck here with $C$ . Have I missed out anything ?







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  • 1




    You have already stated that at $t=0$ you know that $N_0 = C e^k times 0 = C$. So the full solution equals $N(t) = N_0 e^-0.02773t$, and now you can easily calculate $N(45)$
    – Tim Dikland
    Aug 14 at 8:48














up vote
0
down vote

favorite












A particular isotope of Uranium decays to half of its original amt in 25 days. Find the equation relating the amount present as a function of time and find the percentage remaining after 45 days.



Given - $fracdNdt = KN$



I used separable method to solve it to become - $ N = Ce^kt$



Let original amount be $N_0$ when $t=0$



$N_0 = C $2



Given when $N=0.5N_0$ in 25 days,



$0.5N_0 = N_0 cdot e^25k $



$k = - 0.02773$



Thus the general solution - $ N = Ce^-0.02773 t $



I need to find the particular solution using initial conditions to be able to find the amount remaining after 45 days . But I am stuck here with $C$ . Have I missed out anything ?







share|cite|improve this question
















  • 1




    You have already stated that at $t=0$ you know that $N_0 = C e^k times 0 = C$. So the full solution equals $N(t) = N_0 e^-0.02773t$, and now you can easily calculate $N(45)$
    – Tim Dikland
    Aug 14 at 8:48












up vote
0
down vote

favorite









up vote
0
down vote

favorite











A particular isotope of Uranium decays to half of its original amt in 25 days. Find the equation relating the amount present as a function of time and find the percentage remaining after 45 days.



Given - $fracdNdt = KN$



I used separable method to solve it to become - $ N = Ce^kt$



Let original amount be $N_0$ when $t=0$



$N_0 = C $2



Given when $N=0.5N_0$ in 25 days,



$0.5N_0 = N_0 cdot e^25k $



$k = - 0.02773$



Thus the general solution - $ N = Ce^-0.02773 t $



I need to find the particular solution using initial conditions to be able to find the amount remaining after 45 days . But I am stuck here with $C$ . Have I missed out anything ?







share|cite|improve this question












A particular isotope of Uranium decays to half of its original amt in 25 days. Find the equation relating the amount present as a function of time and find the percentage remaining after 45 days.



Given - $fracdNdt = KN$



I used separable method to solve it to become - $ N = Ce^kt$



Let original amount be $N_0$ when $t=0$



$N_0 = C $2



Given when $N=0.5N_0$ in 25 days,



$0.5N_0 = N_0 cdot e^25k $



$k = - 0.02773$



Thus the general solution - $ N = Ce^-0.02773 t $



I need to find the particular solution using initial conditions to be able to find the amount remaining after 45 days . But I am stuck here with $C$ . Have I missed out anything ?









share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Aug 14 at 8:34









user185692

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  • 1




    You have already stated that at $t=0$ you know that $N_0 = C e^k times 0 = C$. So the full solution equals $N(t) = N_0 e^-0.02773t$, and now you can easily calculate $N(45)$
    – Tim Dikland
    Aug 14 at 8:48












  • 1




    You have already stated that at $t=0$ you know that $N_0 = C e^k times 0 = C$. So the full solution equals $N(t) = N_0 e^-0.02773t$, and now you can easily calculate $N(45)$
    – Tim Dikland
    Aug 14 at 8:48







1




1




You have already stated that at $t=0$ you know that $N_0 = C e^k times 0 = C$. So the full solution equals $N(t) = N_0 e^-0.02773t$, and now you can easily calculate $N(45)$
– Tim Dikland
Aug 14 at 8:48




You have already stated that at $t=0$ you know that $N_0 = C e^k times 0 = C$. So the full solution equals $N(t) = N_0 e^-0.02773t$, and now you can easily calculate $N(45)$
– Tim Dikland
Aug 14 at 8:48















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