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.
** **
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 pendulum mass will be at an angle in the 1st quadrant with the x axis in the positive direction.
• 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: ->->->->->->->->->->->-> :
arctan (y / x) = arctan (.2cm / 10cm) = 1.1 degrees
c^2 = a^2 + b^2
c^2 = 10cm^2 + .2cm^2
c = 10 cm
Magnitude is 10cm and direction is 1.1 degrees
• What is the direction of the tension force exerted on the mass?
answer/question/discussion: ->->->->->->->->->->->-> :
-1.1 degrees
• What therefore are the horizontal and vertical components of the tension?
answer/question/discussion: ->->->->->->->->->->->-> :
10cm * cos(1.1) = 10 cm
10cm * sin(1.1) = .2 cm
• What therefore is the weight of the pendulum, and what it its mass?
answer/question/discussion: ->->->->->->->->->->->-> :
5 N = m * 9.8m/s^2
M = .5 kg
• What is its acceleration at this instant?
answer/question/discussion: ->->->->->->->->->->->-> :
9.8m/s^2
** **
15 min
** **
Good start, except that I think you got some of the given information mixed up. Nevertheless it's clear that you understand that part. However you didn't get the tension vector or the acceleration right.
&#Please compare your solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified. &#