Final Temperatures When Hot and Cold Water Mix

Begin with Temperature Versus Thermal Energy to set the vocabulary, then move to the two calculation sheets. Use the vacuum bottle and solar heater sheets as design discussions.

Find energy lost and gained when 80 °C water mixes with 20 °C water and graph the final temperatures. The directions on the page read: Fill in the table and plot final temperature against cold water mass. Then answer. An answer key is included.

Yes, both. We made it for 8th grade energy, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.

Temperature measures the average kinetic energy of the particles in a sample. Thermal energy is the total kinetic energy of all the particles, so it depends on how many there are. A bathtub of warm water has more thermal energy than a cup of hot tea.

Multiply mass by specific heat by temperature change. For example, warming 50 g of copper by 10 °C takes 50 × 0.39 × 10 = 195 J. Calculate Thermal Energy With Specific Heat gives values for water, aluminum, iron and copper.

The vacuum gap blocks conduction and convection, and the shiny surface reflects radiation. Poor conductors such as the stopper and base support slow conduction further. How a Vacuum Bottle Blocks Heat Transfer compares cocoa in a vacuum bottle, a foam cup and a mug.