Childhood summertime physics lesson #1: Leave a Popsicle in the sun, you end up with a puddle.

Adult summertime physics lesson #1: Leave your favorite lipstick in the car?it's time for a new tube!

In just 10 minutes, the temperature inside a parked car can rise 20 degrees above the temperature outside?it's unsafe for kids, pets and these portables:

Cosmetics: Heat can cause them to melt, separate or dry out?and may kill preservatives that prevent bacterial growth. Discard an item if its color, scent or consistency changes. (Soupy sunscreen, anyone?)

Food: Toss eggs, soft cheese, milk, poultry and meat left out (above 40 degrees) for 2 hours or more. Whenever possible, put groceries in an insulated bag or cooler, instead of the trunk.

Medicine: Many drugs become less potent if exposed to sunlight or kept above room temperature (77 degrees). Ask your pharmacist about your prescriptions.

Thankfully, when the car is hot, you can still hydrate?contrary to rumors about toxins in heated plastic, the American Cancer Society (and the Environmental Protection Agency) says stashed water bottles are safe.