Today in class, we opened by looking at a weight of 500g strung between two strings. Both strings were of different lengths, with the one on the left registering a force of 42 meters. Also, the alternate interior angle on the left hand side of the weight had a 64 degree angle. Thus, we had a right triangle on the left, with the longest side being 4 newtons, and the angle closest the weight, 64 degrees. Using sine, it could be determined that the missing side of that triangle opposite the 64 degree angle (Ay) had a force amount of 3.59 newtons. The we looked at the right triangle on the right hand side of the weight, opposite the one on the left.
Pause for a second, and draw a force diagram for the weight. There is the usual gravitational force, which in this case amounts to 5 newtons. Then draw the 2 lines to the right and left of the weight, these are Ax and Bx, and represent the bottom sides of the triangles. Using cosine, it can be determined that each side length (both Ax and Bx) have 1.75 newtons of force. Thus Ax equals Bx. Then, draw 2 arrows pointing upward, one representing side Ay and one representing By. Ay plus By = 5 newtons, the force of gravity. We know Ay, and we know the force of gravity, so by subtracting Ay from 5, we get 1.41 newtons. Then using the Pythagorean theorem with side Bx and By, it can easily be determined that the longer string, on the left has a force of 2.24 newtons.
Also, we learned that velocity is a vector.
Then we looked at a diagram of a boat traveling perpendicular to a river flow at 12 m/s, with the river flowing at 5 m/s. By forming a right triangle, with 5 and 12 as the legs, the speed of the boat as it travels at a sideways angle (along the hypotenuse) can be determined. In a similar way, when the boat is traveling in parallel to the current, with the river, it travels at 17 m/s and against, 7 m/s.
That was all we finished in class, before the bell rang as we were beginning to white board.
Post by Jordan Solano-Reed
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