ALEX ZHAI HAS represented the United States twice at the International Mathematical Olympiad.

Now he is a step closer to doing the same for the U.S. in physics.

Zhai, a senior, was one of only 415 students from around the country — and one of only 30 from Illinois high schools — to advance to the quarterfinals of the U.S. Physics Team selection process.

The students are competing for a spot on the 24-member team, from which five students will be selected to represent the United States at the International Physics Olympiad this summer in Vietnam.

To qualify for the quarterfinal round, Zhai had to take a 75-minute multiple-choice exam that covered material on mechanics. According to physics teacher Jim "Ray" Carrubba, Zhai is the first Uni student to participate in the selection process in about a decade.

"I wanted to learn more physics this year, and there weren't that many venues already in place for me to do that," said Zhai. "So I asked Ray to proctor me for this contest because I figured it would help motivate me and test the thoroughness of my understanding. I don't know why more people weren't interested, but hopefully more people will think about participating next year."

Zhai's next exam, to qualify for the semifinal round, must be taken by March 4. The four-problem, free-response test will last 60 minutes and will cover AP Physics C material in mechanics and electrostatics.

The top 150 students based on the combined scores of their preliminary and quarterfinal exams will advance to the semifinals. That test will be free response and may cover all topics in introductory physics, such as mechanics, thermodynamics and fluids, relativity, nuclear and atomic physics, and waves and optics.

The semifinal exam will consist of two parts lasting 90 minutes each. The exam will be administered between March 13 and 19.

The top 24 students based on the semifinal stage will become members of the U.S. Physics Team, with five to be selected to compete in the 39th International Physics Olympiad, which will take place July 20 to 29 in Hanoi.

This is the first time Zhai has competed in the physics selection process. During the past two summers he has represented the United States at the International Mathematical Olympiad. The 49th IMO will be held July 10 to 22 in Madrid, Spain, overlapping the physics competition.

"There's a scheduling conflict between the international math and physics Olympiads, so it's only possible for me to do one this year," said Zhai. "I don't know whether I can get that far in physics, but it could be a decision to make in a few months."

In 2006 Zhai won a silver medal at the IMO, which was held in Ljubljana, Slovenia. Last summer he won a gold medal and finished seventh overall. The 2007 IMO was held, coincidentally, in Hanoi.

The selection process for the U.S. Physics Team is sponsored by the American Association of Physics Teachers.