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amarswamy (152)

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the bob of a pendulum is given a sharp iht to impart a horizontal vel root of 10gl where l is the lenght of the pendulum . find the tension in the string when


A) the string is horizontal


B)bob is at highest point


C) the string makes an angle 60 with the pward verticle

    
pink_ele (1235)

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by conservation of energy

at horizontal
1/2(10mgl)=mgl+1/2mv^2
so,
v=rt(8gl)
now
mv^2/l=T
T=8mg



at higest point
1/2(10mgl)=2mgl+1/2mv^2
v=rt(6gl)
here
mg+T=mv^2/l
T=7mg


similarly
at 60 deg
1/2(10mgl)=(1-cos 60)mgl+1/2mv^2
v=3gl
now,
mg cos60-T=mv^2/l
T=5mg/2



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