course Phy 121
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13:04:21 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 --> To obtain the final speed and direction of the object, first we know the initial velocity in the x direction, the intial velocity in the y direction is zero. We know how far the object falls, thus using the equation to solve for the velocity in the y direction: v^2 = 2(9.8)(know distance), we get the velocity in the y direction. We can then find the magnitude of the vector arctan(y/x) which will give us the direction. and the magnitude will be magnitude^2 = x velocity^2 + y velocity^2
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13:04:53 ** 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 --> ok
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13:14:09 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 --> Vector Quantities 5 Newtons @ 90 degrees 5 m/s @ 30 degrees 4 kg m/s @ 45 degrees The magnitude is the force, velocity, etc. applied in the direction of the angle. Each of the quantities have 2 vector compenents one in the x axis and one in the y axis.
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13:14:22 ** 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 --> ok
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