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Phy 121
Your 'cq_1_26.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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A simple pendulum has length 2 meters. It is pulled back 10 cm from its equilibrium position and released. The tension in the string is 5 Newtons.
Sketch the system with the pendulum mass at the origin and the x axis horizontal.
answer/question/discussion: ->->->->->->->->->->->-> :
I have a vector 2 meters long in the 4th quadrant that is 10 cm from the y-axis
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Sketch a vector representing the direction of the pendulum string at this instant. As measured from a horizontal x axis, what is the direction of this vector? (Hint: The y component of this vector is practically the same as the length; you are given distance of the pullback in the x direction. So you know the x and y components of the vector.)
answer/question/discussion: ->->->->->->->->->->->-> :
Vector: x-component = .1 meters, y-component = 2 meters, magnitude = 2.002 meters. For the direction I used arctan(2/.1) =87.1 degrees. I think this is the angle opposite of that which I wanted to find, so the direction is really 2.9 degrees (really 272.9 degrees since it is directed down and right)
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What is the direction of the tension force exerted on the mass?
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The tension force on the mass is opposite so it is up and left at 92.9 degrees
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What therefore are the horizontal and vertical components of the tension?
answer/question/discussion: ->->->->->->->->->->->-> :
x-component = 5cos(92.9) = -.25 N, y-component = 5sin(92.9) = 4.99 N
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What therefore is the weight of the pendulum, and what it its mass?
answer/question/discussion: ->->->->->->->->->->->-> :
If the y-component of Tension is 4.99 N then the actual mass must create a force of 4.99 N when hanging directly down. 4.99N = 9.8 m/s^2 * mass, mass = 0.509 kg
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What is its acceleration at this instant?
answer/question/discussion: ->->->->->->->->->->->-> :
Acceleration straight down is 9.8 m/s^2 due to gravity
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&#Very good responses. Let me know if you have questions. &#