400
The relationship between current (I), voltage (V) and resistance (R) is given by I=V/R. Suppose 2 amps of current flows through a resistor. At the moment when the resistance is 5 ohms and is changing at 2 ohms/minute, what is the rate of change of voltage?
0=R(t)V'(t)-V(t)R'(t), R(t)=5, V(t)=10, R'(t)=2
So 5V'(t)=10(2). What is 4 volts/min?