Kinematics Question 770

Question: A bob of mass 10 kg is attached to wire 0.3 m long. it’s breaking stress it’s 4.8 × 107 N/m2.The area of cross section of the wire it’s 10?6 m2.The maximum angular velocity with which it can be rotated in a horizontal circle [Pb. PMT 2001]

Options:

A) 8 rad/sec

B)4 rad/sec

C) 2 rad/sec

D)1 rad/sec

Show Answer

Answer:

Correct Answer: B

Solution:

Centripetal force = breaking force therefore mω2r= breaking stress ´ cross sectional area therefore mω2r=p×A

therefore ω=p×Amr=4.8×107×10610×0.3 ω=4rad/sec



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