Grade 11Mechanics

A boy is hanging from a horizontal branch of a tree.The tension in his arms will be maximum when the angle between his arms will be what????

Sayani

8 Years agoGrade 11

2 Answers

Arun

Approved Tutor Answer8 Years ago

The resultant of tensions in the arm must be equal to weight F (= mg)

Hence

F² = P² +P² + 2P² cos @

F² = 2P²( 1+ cos@)

P² = F²/2(1+cos @)

P is max when (1+ cos@ ) is min

Cos @ = -1

@ = 180 ° is not possible

Hence cos @ = -1/2

Hence

@ = 120 °

Anurag

8 Years ago

Let tension be t so

Angle between arms be @ and @

F=mg

So by resolution we get

2rcos@=mg

r=mg/2cos@

Diffrenciate it and ill get ans as 120'

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A boy is hanging from a horizontal branch of a tree.The tension in his arms will be maximum when the angle between his arms will be what????

Sayani

2 Answers

Arun

Anurag

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