Exam 1 2010

# Exam 1 2010 - Zoology 4472 Avian Biology Exam #1 Spring...

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Zoology 4472 Avian Biology Exam #1 Spring 2010 NAME _______________________ Please answer all questions. Adjust your time according to the point value of each question. Place your name in the upper right corner of every page! This exam is worth 45 points. Good luck! 1a) (2 points) Explain the relationship between Bernoulli’s principle and lift. Provide a diagram and label it. b) (2 points) Now think about how Bernoulli’s principle can be used to explain how baseballs “fly”. A pitcher can throw a baseball so that it swerves to the right or left as it approaches the batter (so-called “curve balls”) or so that it drops precipitously or tends to maintain altitude (“sinkers” and “floaters”, respectively). The pitcher accomplishes this by making the ball spin as it’s released. Consider the drawing, below. The ball is traveling from left to right, from the pitcher to the batter. It is spinning clockwise – the top of the ball spins towards the batter. Explain how and why differences in dynamic pressure are likely – where is dynamic pressure highest? Lowest? (Hint: you’ll likely find it helpful to draw the flow of air over the ball.) spin Pitcher Is Here XX Ball is traveling in this direction c) (2 points) What is going to happen to the ball’s trajectory as it approaches the batter? Will it rise or fall more than would be expected without a spin? Will the spin cause it to curve to the right or left? Explain, using a diagram.

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d) (1 point) Part II (unrelated to parts a-c). As you know, the principles of flight that we’ve learned are also relevant to planes. Here’s an example, which we’d like you to figure out: A small plane recently crashed in Ohio, killing some local residents who were on board. Here’s what was reported in the Gainesville Sun last Thursday: “A witness to an Ohio plane crash earlier this month, which killed two North Florida men and the parents of an Alachua County businessman, said its wings were at almost a 90-degree angle relative to the ground as the aircraft approached the runway…” The plane was almost certainly “banking” to position itself for landing. The pilot had tilted one wing up and the opposite wing down. This would result in two things: (1) the plane turns in the direction of the lower wing and (2) the plane loses altitude. Normally, these changes are fine. What caused the crash is that the lower wing was pointing straight down and the upper wing straight up. That’s the answer. We’d like you to explain it. Start by drawing a front view of a plane, flying directly towards you and with its wings level (not tilted). Using vectors to show force, draw the net force each
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Exam 1 2010 - Zoology 4472 Avian Biology Exam #1 Spring...

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