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# how did they get this? watch

1. the circled part.

newton's law of cooling is

dT/dt = -k(T-Ts)

(T- temperature of cooling body, Ts- temperature of surrounding)

By defining x=(T-Ts), determine the differential equation for x. Write down the solution of this equation.

thanks!
2. Which line: or ?
3. (Original post by DFranklin)
Which line: or ?
both, sorry
4. Getting the 2nd line from the first is trivial - you've defined x to equal , so .

For the first bit, do you know how to solve a separable differential equation?
5. (Original post by DFranklin)
Getting the 2nd line from the first is trivial - you've defined x to equal , so .

For the first bit, do you know how to solve a separable differential equation?
ah great thanks

no i don't understand how to solve a sep. diff. equation. it seems to be my problem for every question like this, i should get that sorted!

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