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 **

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

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

I think it is directed towards the center

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It's not clear what you mean by 'the center'.

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The tension is directed toward the top of the string.

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

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

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

T_y = 5 N * 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: ->->->->->->->->->->->-> :

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

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What is its acceleration at this instant?

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

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

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