Rates of change Q
Sphere of radius R melts such that the radius after time t is r and the rate of change is given by:
dr/dt = -r
If T is the time taken for the radius of the sphere to decrease to (1/4)R, show that T = ln4
-----
When I integrate I get
ln r = -t + lnA
but don't know what to do from there (if that's right)
Thanks.
dr/dt = -r
If T is the time taken for the radius of the sphere to decrease to (1/4)R, show that T = ln4
-----
When I integrate I get
ln r = -t + lnA
but don't know what to do from there (if that's right)
Thanks.
You know that when t = 0 then r = R.
Use this to solve your constant of integration and you are home.
Use this to solve your constant of integration and you are home.
Original post by Mr M
You know that when t = 0 then r = R.
Use this to solve your constant of integration and you are home.
Use this to solve your constant of integration and you are home.
Thank you!
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