BRUCE S.'s Blog at WyzAnt.com

Ice and Water

posted by WyzAnt tutor: BRUCE S.

Hi!

My 7 year old grandson just received a chemistry set (Guess who gave it to him.)

A week later he posed the following question:

A gallon of ice at 10 F and gallon of water at 50 F are mixed together. What is the final temperature of the mixture?

This is not a trivial question and in fact involves at least 3 basic principles of thermodynamics. Personally I have never seen this type of question on any exam, quiz, homework problem set or college prep exam.

Can you determine the answer? Good Luck!

PS Assume the ice and water are in perfectly insulated containers before and after mixing. (Without this assumption the problem is REALLY messy.)

Ice Skating Anyone?

posted by WyzAnt tutor: BRUCE S.

Winter is the time for ice skating and although most ice skating today is done on a rink, it is still a past time that occurs on lakes and ponds. So, have you ever stopped to think about why water freezes on the top of the lake's surface and not at the bottom of the lake? (No ...it is not because 'otherwise the fish in the lake would freeze'.)

Another Conundrum

posted by WyzAnt tutor: BRUCE S.

The very large garbage truck of mass M and a sporty Miata sports car of mass m have equal momentum. Which vehicle takes the most work to stop and can you derive the equations that supports your answer?

The Dragon Fly and The Delivery Van

posted by WyzAnt tutor: BRUCE S.

A dragon fly flies down a isolated Texas road looking to eat mosquitoes when suddenly it collides head-on with a big delivery van. You know the results but can you say whether the forces on the dragon fly and the van are equal or unequal and can you justify your answer with physics?