cq_1_261

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PHY 201

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.

** CQ_1_26.1_labelMessages.txt **

Samantha Rogers

PHY 201

Seed 26.1

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 sketched the system

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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: ->->->->->->->->->->->-> :

 angle = arcTan(200 cm / (-10 cm) ) = 2.9 deg + 90 deg = 92.9 deg.

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• What is the direction of the tension force exerted on the mass?

answer/question/discussion: ->->->->->->->->->->->-> :

 The tension force on the mass is directed along the string, at angle of 92.9 deg as measured counter clockwise from the positive x-axis.

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• What therefore are the horizontal and vertical components of the tension?

answer/question/discussion: ->->->->->->->->->->->-> :

 the tension is 5 N and the components are

T_x = 5N * cos(92.9 deg) = .25 N

T_y = 5N * sin(92.9 deg) = 5 N

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• What therefore is the weight of the pendulum, and what it its mass? 

answer/question/discussion: ->->->->->->->->->->->-> :

 the pendulum is in equilibrium, the weight is the same as the vertical component of the tension (5N).

Mass is m = weight / g = 5 N / (9.8m/s^2) = .51 kg

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• What is its acceleration at this instant? 

answer/question/discussion: ->->->->->->->->->->->-> :

 a = Fnet / m = /25 N / (.51 kg) = .49m/s^2

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&#Very good responses. Let me know if you have questions. &#