If 25.0g of h2o at 11.2 celsius is combined with 75.0g h2o at 87.2 degree celsius, what is the final temperature of the mixture?

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.