# Math Help - A synthetic radioactive element decays at a rate proportional to its mass ....

1. ## A synthetic radioactive element decays at a rate proportional to its mass ....

A synthetic radioactive element decays at a rate proportional to its mass.
(a) write down a differential equation to represent this situation.
(b) If 30% of the element has decayed after 24 hours, what percentage is left after 48 hours?
c) How long does it take for 90% of the element to decay?

2. ## Re: Help me with this qeustion, please

One for free:

Mass as a function of time: m(t)

Decay Rate of Element: dm/dt

Go!

3. ## Re: Help me with this qeustion, please

Originally Posted by TKHunny
One for free:

Mass as a function of time: m(t)

Decay Rate of Element: dm/dt

Go!
And because I'm so nice, one for free from me too :P

If a is proportional to b, then a = kb, where k is some constant.