Reminds me of my (old) college professor who once gave a test where the first question was about a sailboat with an on-board fan blowing into the sail.
It was meant to be an easy question to see if students understood Newton's third law, but one student filled in the entire test with momentum calculations showing that the boat would actually move forward at X velocity because the sail would essentially redirect some % of the air backwards like a reverse thruster (conservation of momentum). He left the rest of the test blank because he blew the whole time limit on the first question.
The professor was perplexed when grading this student's exam and built a "sailboat" out of a pinewood derby car with a dowel rod mast and aluminum foil sail. He taped a handheld fan to the car, pointed into the sail, and indeed, the car moved forward (this part he demoed to the class as he was telling the story and just before he did it, he took a poll to see how many people thought it would move forward, backward, or stay still - "stay still" won the poll)
The student reportedly got 100% on the test and the professor threw out that question on future exams.
It was meant to be an easy question to see if students understood Newton's third law, but one student filled in the entire test with momentum calculations showing that the boat would actually move forward at X velocity because the sail would essentially redirect some % of the air backwards like a reverse thruster (conservation of momentum). He left the rest of the test blank because he blew the whole time limit on the first question.
The professor was perplexed when grading this student's exam and built a "sailboat" out of a pinewood derby car with a dowel rod mast and aluminum foil sail. He taped a handheld fan to the car, pointed into the sail, and indeed, the car moved forward (this part he demoed to the class as he was telling the story and just before he did it, he took a poll to see how many people thought it would move forward, backward, or stay still - "stay still" won the poll)
The student reportedly got 100% on the test and the professor threw out that question on future exams.