course Phy 121 CʾzxymƇassignment #021
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09:42:16 Explain how to obtain the final speed and direction of motion of a projectile which starts with known velocity in the horizontal direction and falls a known vertical distance, using the analysis of vertical and horizontal motion and vectors.
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RESPONSE --> You first have to get the units the same for the vertical and horizontal direction. That means finding out the speed using the distance in the horizontal direction. Then, the horizontal speed will be the x component and the vertical speed will be the y component. The total speed will then be : horz ^2 * vert^2 = total speed ^2. Then to find the magnitude, you would do: arctan (y/x).
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09:44:09 ** The horizontal velocity is unchanging so the horizontal component is always equal to the known initial horizontal velocity. The vertical velocity starts at 0, with acceleration thru a known distance at 9.8 m/s^2 downward. The final vertical velocity is easily found using the fourth equation of motion. We therefore know the x (horizontal) and y (vertical) components of the velocity. Using the Pythagorean Theorem and arctan (vy / vx) we find the speed and direction of the motion. **
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RESPONSE --> I just thought about a ratio to get the second velocity instead of actually plugging it into an equation of motion. It makes more sense to solve it individually.
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09:48:25 Give at least three examples of vector quantities for which we might wish to find the components from magnitude and direction. Explain the meaning of the magnitude and the direction of each, and explain the meaning of the vector components.
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RESPONSE --> Three examples of vector quantities are displacement, velocity and acceleration. The magnitude of displacement would be the total distance traveled between the two vectors. The direction would be the direction of the total travel. The magnitued of velocity is the total speed between the vectors. The direction weold be which was the total speed is going. The magnitude of acceleration is the toal accleration between the two vectors. The direction of the acceleration is the direction the object would be going cmopared to the two vectors.
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09:50:33 ** GOOD STUDENT RESPONSE: Examples might include: A force acting on an object causing it to move in an angular direction. A ball falling to the ground with a certain velocity and angle. A two car collision; velocity and momentum are both vector quantities and both important for analyzing the collision.. The magnitude and directiohn of the relsultant is the velocity and direction of travel. The vector components are the horizontal and vertical components that would produce the same effect as the resultant.
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RESPONSE --> I didn't think that you wanted actual examples. I see how these actual examples can be a bit more practical to discuss vectors.
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