Verified Solution • 2025–26 Session moderate

QJEEM21Ph7a79: JEE Main 2021 Physics - Class 11 JEEM21Ph7a79 Solution: Two blocks of masses 3 kg and 5 kg are connected by a metal…

Two blocks of masses 3 kg and 5 kg are connected by a metal wire going over a smooth pulley. The breaking stress of the metal is 24π×102{{24} \over \pi } \times {10^2} Nm-2. What is the minimum radius of the wire ? (Take g = 10 ms-2)

JEE Main 2021 (Online) 26th August Evening Shift Physics - Properties of Matter Question 157 English

Multiple Choice Options

  • A 125 cm
  • B 1250 cm
  • C 12.5 cm
  • D 1.25 cm

Step-by-Step Verified Solution

JEE Main 2021 (Online) 26th August Evening Shift Physics - Properties of Matter Question 157 English Explanation

T=2m1m2gm1+m2=2×3×5×108T = {{2{m_1}{m_2}g} \over {{m_1} + {m_2}}} = {{2 \times 3 \times 5 \times 10} \over 8}

=752= {{75} \over 2}

Stress =TA= {T \over A}

24π×102=752×πR2{{24} \over \pi } \times {10^2} = {{75} \over {2 \times \pi {R^2}}}

R2=752×24×100=38×24{R^2} = {{75} \over {2 \times 24 \times 100}} = {3 \over {8 \times 24}}

⇒\Rightarrow R = 0.125 m

R = 12.5 cm

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring