The Voltage v , Current I and Resistance R are related by the equation V=IR. Suppose that V is increasing at a rate of 2 volt/sec, while I is decreasing of the rate of 1/5 (amp/sec ). Let t denote time in seconds.

Question

Find the rate at which R is changing when V=40volts and 1=2 amp .

Answer 1

V = IR
dV/dt = R dI/dt + I dR/dt

Now just plug in your numbers.