2007-10-15
Homework due tomorrow.
Today's nonsense
- Katie and Aly absent on Friday from calculus.
- Brandon went to go see the pig. They let the pig out. The pig would not go back in the pin. So, a girl there that has her own pig, got her whip out, and started hitting the pig, and so the pig bruises and marks easily, and so there was a mark over the pig, and Brandon was very distraught over it, and he said, "I can't do this, I can't hurt the pig like that," and so now how is he going to ever train the pig? The pigs are stubborn. They squeel often. Apparently they mark easily, but it goes away quickly. How is he going to send that pig to the slaughter house? The story is going to have to be that the pig is going to the uncle's farm. We are going to have to take pictures of the pig and send them to Brandon every so often and show that he's still alive and not slaughtered .. right.
- What happens to the dogs in the dog races that chase rabbits and can no longer chase? Can you just shoot them? Isn't that against the law?
- Dakota sounds like he's on the redneck side of his family. "I've shot several dogs," - Dakota.
- "Why not" and knots in boy scouts and apparently in Girl Scouts you don't learn knots? What do the boy scouts do with all the knots if the girl scouts don't need them? Maybe the girls weren't paying attention?
What's a slug? (Unit of measure)
Not the mollusk.
Today we are doing some examples similar to said homework. The lab is going to be due later, as soon as we can get to it, and if we did the lab today then there'd be homework griping tomorrow and so to avoid political disaster ... So, when we last left off. Related rates. That's what they are doing in AB. They're so simple. Yeah, you look at them again now this year, and oh, wait, you don't think they are simple? They will be on the next test. Find an AB person to help you, get some tutoring. Are you ready for some examples?
1) A single force of 20N (kilogram meter per second squared) acts on a particle of mass m_1. The particle starts from rest and travels in a straight line a distance of 24 m in 4 sec. What's the mass of the object? Use the position = 0.5aT^2 equation.
2) A certain force, F_1, causes an acceleration of 5 m/s^2 when it acts on an object of mass m, sliding on a frictionless surface. Find the acceleration of the same object if ... if two equal forces of F_1 act at 90 degrees on the same object. What's the magnitude of F_1? Anyway, it seems that what you have to do is combine the force vectors (because they are at 90 degree angles) and then there's the mangitude of the combined forces, which you use later after you discover F_1 = 5m, and then you show that m = F_1 / 5, and you can plug that into the the new acceleration that you are trying to find.
"For every rule there is an exception, and that exception is Dakota." - Spiller
"Your whole room is a distraction." - Dakota's response.
2B) Two equal forces of F_1 act at 60 degrees on the same object. So we need our two forces, and add them together. If you want to keep it simple, what I would do is have the first vector going to the right (F_1i + 0j) and the other one would be going up at an angle of 60 degrees. If these two forces ar at 60 degree angles, then ... is acceleration going to be greater or less than, and why do you think? The closer the two forces are, then it's going to be twice the force, and so double the acceleration, the closer they are the more effective they are. Your intuition was indeed correct.
3) A 10 kg object is subjected to forces F_1 = ( 3i + 5j ) and F_2 = (5i - 11j) N. The object is at rest, located at (-3,2) m at time t=0. So, what is the object's acceleration? Find the overall net force (F_{A+B}) which is 8i - 6j. Isn't acceleration equal to F/m? So in this case, the mass is 10, and so that's Force / 10, so that's .8i - .6j. What's the velocity at time T=4 sec? Velocity is the integral of acceleration, so integrate acceleration, and you'd get (0.8T + C)i - (-.6T - C)j. The object is at rest, so these two C values are zero, since you were told that, and