Toronto: A world-famous Canadian university stumped more than 6,000 high school students from around the world who took this year's Sir Isaac Newton (SIN) examination.

The examination offered by the university had a question that featured California governor Arnold Schwarzenegger throwing Barack Obama and Hillary Clinton with equal speeds from the top of a cliff.

The question was: Obama is thrown upwards at an angle A above the horizontal. Clinton is thrown downwards at an angle B below the horizontal. Which presidential candidate has the greater speed of impact with the water in the lagoon below? (a) Obama (b) Clinton (c) Both have the same speed of impact (d) Depends on the candidates' masses (e) Depends on A and B.

Rohan Jayasundera, director of the examination, said that this was just one of the problematic questions posed to the students who wrote this year's exam in May, offered by the university's physics and astronomy department to encourage the teaching and learning of physics.

Jayasundera said such political and topical humour has marked SIN exams for years, and this year was no exception.

``The SIN test is meant to challenge the best students to apply basic physics in problem situations,'' he said.

``The goal of this test is to stimulate interest in physics in high schools, both among the students and their teachers.''

Canada's Junjiajia Long from Ottawa's Glebe Collegiate Institute topped with a score of 96. Yan Li and Shuo Shan from Toronto's Dr Norman Bethune Collegiate Institute came in second and third with a score of 93 and 91 respectively.

In a statement, the university said, ``The two-hour contest was computer-scored, but the top 200 papers were hand-marked to select SIN scholarship winners and book prizes.

``SIN entrance scholarships of $5,000 are offered to students who study honours physics at the university, in either the regular or co-operative (work-study) programme.''

The SIN exam was started in 1969 when 1,500 students from 300 high schools participated in it.

Now the number of students has quadrupled, with contestants coming from all over the world, including India, China, Switzerland, Hong Kong and Singapore.

Over the years, many challenging questions have appeared on the SIN exam, and the questions (and their solutions) have been published as a book entitled A Decade of SIN, the university said. IANS