One impossible question a day

Every school afternoon this page carries a new physics question, and the worked solution goes up the next morning at 7:00 Eastern. The question loads here when you open the page. If you are reading this text instead, your browser has not run the page script yet.

Each day comes in three levels, and you open the next one by answering the one you are on.

Level 1, PhD dropout. Two linked steps, or one idea that is not obvious. Even Mr. Tuna can answer it.

Level 2, CalTech. A real insight, with a tempting trap that catches anyone taking a shortcut.

Level 3, Lucasian. Genuinely hard for a strong AP student.

Levels 1 and 2 are free for anyone to read, with every hint, and no account is needed. Level 3 is for students in the courses. A tutor works through the question with you rather than handing over the answer, and nothing you type here is graded.

Older questions stay up in the archive. The day-by-day notes for each course are free to read as well: AP Physics 1 and 2, AP Physics C, Conceptual Physics, and Physics and Engineering Research. If you need something that is not posted publicly, you can ask for access.