Phy 231
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: ->->->->->->->->->->->-> :
The mass of the pendulum is located at the origin, therefore the equilibrium position of the pendulum is at x = -10cm. The angle formed with the positive x axis and the string of the pendulum is just past 90 degrees.
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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: ->->->->->->->->->->->-> :
You find the angle by taking the arctan of 10cm / 2m = arctan .1/2 = 2.86 degrees. Add 90 degrees onto the answer because it is in the second quadrant and the direction of the string is 92.7 degrees
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• What is the direction of the tension force exerted on the mass?
answer/question/discussion: ->->->->->->->->->->->-> :
The tension is in the same direction as the string: 92.7 degrees.
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• What therefore are the horizontal and vertical components of the tension?
answer/question/discussion: ->->->->->->->->->->->-> :
x component: 5N cos 92.7 = -.236 N
y component: 5N sin 92.7 = 4.99 N
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• What therefore is the weight of the pendulum, and what it its mass?
answer/question/discussion: ->->->->->->->->->->->-> :
Y component of the tension is equal to the weight, so the weight of the mass is 4.99N. The mass is 4.99N / 9.8m/s^2 = .509 kg.
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• What is its acceleration at this instant?
answer/question/discussion: ->->->->->->->->->->->-> :
The acceleration at that point is 9.8m/s^2 – the acceleration due to gravity.
That would be the acceleration if the string was cut and the mass dropped without any resistance.
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20 minutes
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See my note on that last question. Very good up to that point.
&#See any notes I might have inserted into your document. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your solutions with the expanded discussion at the link
Solution
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