Plotting Curve of Newton’s Law of Cooling

Basic Theory Behind The Experiment

Newton’s Law of Cooling states that the rate at which an object’s temperature changes is directly proportional to the temperature difference between the object and its surroundings. In simpler terms, if an object is hotter than its surroundings, it will cool down, and if it’s cooler, it will warm up until it reaches thermal equilibrium – the point where there’s no net heat transfer.

The mathematical expression of Newton’s law of cooling is given as

Where,

T = temperature of the body at time t
T₀=the ambient temperature (i.e., The temperature of the surroundings) and k = proportionality constant

What You’ll Need

Copper calorimeter
Two thermometers
Stirrer
Open double-walled vessel
Stopwatch
Burner
Liquid

Procedure

Place the copper calorimeter in an open double-walled vessel above the burner. Fill the vessel with water.
Measure the initial temperatures of the calorimeter and water using thermometers.
Start the burner, stir water, and record temperatures at intervals until the calorimeter stabilizes.
Calculate temperature differences between the calorimeter and water at each interval.
Graph time intervals vs. temperature differences on graph paper or software.
Curves on the graph should show a decreasing trend as the system approaches thermal equilibrium.
Compare the curve with theoretical predictions based on Newton’s Law of Cooling.

Observations

The observation in this experiment is seen through the graph you plot. As time progresses, the temperature difference between the heated object (calorimeter) and the cooling medium (water) decreases. In other words, the rate at which the calorimeter cools down slows down over time.