Exam 1 solutions

# Exam 1 solutions - Exam 1 solutions Name: Instructions:...

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Exam 1 solutions Physics 203 Name: Instructions : The responsibility is yours to show me that you understand what you are doing so please show all your work. If you feel you are stuck on a particular part explain as much of your thinking as you can so I can give you the maximum amount of partial credit (explain the strategy you are using, draw pictures/graphs, etc.) Use the backs of the exam pages if you need extra space. Each problem is worth 10 points. The problems are not all of the same difficulty though, so budget your time wisely. The last pages of the exam contain useful physical constants, conversion factors, and other data. Please check there first if you feel you need more information than is given in the problem. Good luck! 1. An acrobat steps off a high platform. She falls 10.0 m onto a large trampoline (example shown here) which stretches then launches her back upwards to a height of 6.0 m. Draw a motion diagram and a force diagram for the acrobat during each of the following parts of the her motion: a. While she is falling towards the trampoline. b. While she is in contact with the trampoline. c. While she is traveling upwards after bouncing off the trampoline. For part a., the only significant force being exerted on the acrobat is the gravitation force exerted by the Earth. (Next page) Score 1: 2: 3: 4: 5: Total /50

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For part b., since the acrobat is in contact with the trampoline, it will exert a force on her. It points upward, and since she is now accelerating upwards it must be greater in magnitude than the gravitational force exerted by the Earth. 5 v is shorter than 1 v because the acrobat doesn’t spring back to the same height that she started at. For part c., only the gravitational force exerted by the Earth is significant. Since she is slowing down, her acceleration points in the opposite direction to the direction she is traveling. E on A F 1 v 2 v 3 v v T on A F E on A F 1 v 2 v 3 v v 4 v 5 v F 1 v 2 v 3 v v
2. Refer to the situation in the previous problem. a. Predict how fast the acrobat is traveling when she contacts the trampoline. b. While she was in contact with the trampoline, the trampoline stretched downward 2.0 m before springing back. Predict the length of time she was in contact with the trampoline, and her acceleration during that time. c. Describe any assumptions that you made in parts a. and b. I’ll assume the drag force exerted by the air on the acrobat does not significantly affect her motion. With that assumption, her acceleration will be constant, so I can use kinematics. The initial moment will be when the steps off the platform, and the final moment will be just before she touches the trampoline. The origin will be at the trampoline, and the positive y direction will point upwards.

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## This note was uploaded on 06/22/2009 for the course PHYS 1101 taught by Professor Richardson, b during the Fall '08 term at Cornell University (Engineering School).

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Exam 1 solutions - Exam 1 solutions Name: Instructions:...

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