How do you work out the potential diffrance

The potential difference is the drop in voltage that occurs across a resistor as current flows through it in a circuit, potential difference or voltage(V) = current (I) *resistance (R), or to abbrevate V = I*R. In this case, I = 5amps and R = 10 ohms, so V = 5 * 10 = 50volts

v=ir = 3x15 =45 v

graph slopes whilst gas cools, then it is flat whilst conensation to liquid happens, the coolong liquid then graphs as a slope when it solidifies graph is flat

latent heat