Your assignment is shown on your schedule. When I ask how far the first book can stick out, I mean the following: Assume the books project over the left edge of the table and each book projects to the left of the book below it. Tell me how far the left edge of the top book projects to the left from the table's left edge. This is simply the sum of x1 + x2+ x3 +x4...........etc. Assume all teh weight of the books above Book N is applied at the left edge of Book N.
You really should try hard to get this. I don't care so much that you get the right number, but I do want you to exercise those gray cells that have been sleeping for ten weeks ( or maybe 16 years).
Read through the notes again ( or for the first time) they will help.
To solve the last problem on the balance worksheet from Friday required that you realized that weight of the ruler can be assumed to act at the 50 com mark, i.e. the middle. Then apply our rule for balancing the weight of the 100g mass times its distance from balance point must = the weight of the 200 g ruler times its distance from the balance point. Thus the balance point must be twice as far from the 100 g mass as it is from the 50 cm mark. How do you divide the distance between two point so that one part is twice as large as the other. You divide it into thirds andthe larger part is 2/3 of the total and the smaller part is 1/3. This gives you a 2 to 1 ratio between the larger and smaller parts.
Since the the weight is at 30 cm, the balance point must 2/3 x (50 cm - 30 cm) from the 100g mass, and 1/3 x (50cm-30cm) from the 50 cm mark. Thus the balance point is at 6.7 cm from 50 or the 43.3cm mark.
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