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UPDATE: Homework 2 assignment and open thread

January 23rd, 2009 · 2 Comments

Let’s try this again…last time there was no discussion on the homework, and maybe that was because the assignment was not too hard? Let’s use this open thread to discuss and help each other with the homework, eh?

Prob. 2-6, 2-7, 2-15, 2-19

This assignment is due at the beginning of class on Friday 1/30 (NOON!). NO late homework will be accepted.

Feel free to get some help if you need it using Mathcad or a similar tool–the trig can sometimes be a bit of a pain, and Mathcad may be able to help. And if you discover any useful tricks to working with the trig, feel free to post them here as a comment.

Here’s the UPDATE: feedback from HW #1. It still seems clear that some students are struggling to develop a clear, consistent problem solving approach. So let me be clear about how HW will be graded. Our rubric for grading HW will be the following: about 1/4 of the credit will be for the problem set-up (including drawing a good diagram, FBD, etc. with labels and coordinate system, etc.), about 1/2 for the procedure and mathematics of solving the problem (are you clearly stating your steps? do you explicitly say what you are trying to do? is it easy to follow your thought process?), and about 1/4 for the actual mechanics of the solution (punching the numbers, performing specific mathematical action like algebra or derivatives, and coming up with the final number–including units!). You’ll also notice that the features contained in the rubric are the components of a good problem solving approach. These numbers are approximate, because (for example) some problems will be more intensive on the calculation part and have really simply diagrams. So the weighting of these might shift just a bit depending upon the problem. Point is, you now know how we will be grading the homework, so you should execute your problem solutions accordingly.

Tags: MAE 231 Strength of Materials · Homework (MAE 231)

2 responses so far ↓

  • 1 cms2vp // Jan 29, 2009 at 9:58 pm

    For 2-6 it may help you to create a triangle between A, B, and B’ after you calculate the change in length of BD for the given max normal strain. If you extend this triangle then you can see how much vertical displacement occurs at P.

  • 2 cms2vp // Jan 30, 2009 at 9:32 am

    **Correction** You have to compare the triangles A,B,B’ and A,C,C’ to see which rope will reach its maximum normal strain first. This rope will be the limiting factor for the system, so you will use that triangle to calculate the displacement at P

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