Brewed coffee is often too hot to drink right away. you can cool it with an ice cube, but this dilutes it. or you can buy a device that will cool your coffee without dilution - a 200 aluminum cylinder that you take from your freezer and place in a mug of hot coffee.

q)if the cylinder is cooled to -20c, a typical freezer temperature, and then dropped into a large cup of coffee (essentially water, with a mass of 500g ) at 85c, what is the final temperature of the coffee? answer in 2 sig figs and answer in celsius.