#$&*
course Phy 201
4/28/13 515pm
Query 21 If your solution to stated problem does not match the given solution, you should self-critique per instructions at http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm.
Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it. This response should be given, based on the work you did in completing the assignment, before you look at the given solution.
If your solution to stated problem does not match the given solution, you should self-critique per instructions at http://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm.
Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it. This response should be given, based on the work you did in completing the assignment, before you look at the given solution.
021. `query 21
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Question: `q Explain how to obtain the final speed and direction of motion of a projectile which starts with known velocity in the horizontal direction and falls a known vertical distance, using the analysis of vertical and horizontal motion and vectors.
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Your solution:
First determine the vertical velocity at the instant it hits the floor. The horizontal velocity doesn’t change.
These are the x and y or horizontal and vertical components. Using sqrt(x^2+y^2) we can find the magnitude. Using arctan(y/x) we can find the angle.
confidence rating #$&*:
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Given Solution:
`a** 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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Self-critique (if necessary):
ok
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Self-critique Rating:
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Question: `qGive 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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Your solution:
I don’t really know what you want here. Do you want real life examples? Like a missile being launched and the people that program, the missile need to know how far and how high it should travel so they can figure out the amount of force needed to hit the target. Another example could be trying to figure out the optimal angle for a shot putter to throw the shot put. You need to know how much force the thrower exerts to determine which x and y comp result in the greatest throw
confidence rating #$&*:
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Given Solution:
`a
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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Self-critique (if necessary):
I wasn’t sure exactly what you were looking for. My examples were a little more complex and I would not be able to solve any of them.
@&
Those are good examples.
That reminds me of the article I read about a high school kid who came up just short of 60 feet. I assume that's with a 12-pound shot, but it still makes my shoulder hurt to think about it.
The mechanics of throwing, and the optimal angle for distance, vary from individual to individual. But if you had the thrower a video of the shot-put you could make a very good estimate of the height from which it was released, and you could time it to figure out how long it was in the air. With that information you could use the techniques you're using in this course to determine the initial angle. The algebra would be a little more complicated, but the setup would be familiar.
*@
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Self-critique Rating: ok
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#*&!
This looks good. See my notes. Let me know if you have any questions.