Your 'cq_1_21.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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Assignment 21 Seed Question 1
A ball is tossed vertically upward and caught at the position from which it was released.
• Ignoring air resistance will the ball at the instant it reaches its original position be traveling faster, slower, or at the same speed as it was when released?
answer/question/discussion: The ball will be traveling at the same speed it was when it was released, as the KE will be equivalent from the toss to when the ball is caught. This is because KE before = KE after, because energy is conserved.
• What, if anything, is different in your answer if air resistance is present? Give your best explanation.
answer/question/discussion: If air resistance is present, then the ball will go slower up and slower down, but the impact overall will be the same.
Air resistance will enhance the slowing effect of gravity on the rising ball, which will as a result not rise as far. So the falling ball won't drop as far, resulting in a lesser final speed.
Air resistance will then oppose the speeding up of the falling ball, so that the final velocity will be even less.
For a dense ball tossed gently upward, the effect of air resistance will be small, perhaps negligible with respect to the accuracy of our instruments. If the ball is less dense, and/or speeds are greater, air resistance will have a greater effect.
In terms of energy conservation, assuming 'still' air (i.e., no wind, no rising and falling of air), air resistance acts always in the direction opposite motion and therefore does negative work on the object. This results in less increase (or greater decrease) in the kinetic energy of the object.
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This took me about 10 minuets to do.
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&#Good work. See my notes and let me know if you have questions. &#