How can you make cold water boil faster than warm/ hot water?
Assuming that the volume of water and the amount of heat are exactly the same, one way of getting the cold water to boil first is to increase its pressure. That’s why it takes longer to cook something on the mountains than at the sea level – pressure at sea level is way higher (at sea level is =9.8 m/s^2). One way of testing it is to add the cold water in a pressure cooker and measure the time it takes for the water to reach 100 degrees Celsius (or 232 Fahrenheit). Then you take the same amount of water in a higher initial temperature (warm/hot) and put it on any regular pan and make the same test. If the warm/hot water is not really close to its boiling point you could come up with a smaller time to boil the cold water. As far as adding something to the cold water, the idea is to add something that would reduce the specific heat of the water (which is 1 calorie/gram °C or 4.184J/g °C). That is the case because the relationship between heat and temperature change is given by: Q = m*c*d
