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Physics · SYSTEMS OF PARTICLES AND ROTATIONAL MOTION
हिन्दीA uniform horizontal bar of length \( 70\text{ cm} \) and mass \( 4.0\text{ kg} \) rests on two knife edges placed \( 10\text{ cm} \) from each end. A load of \( 6.0\text{ kg} \) is suspended at a distance of \( 30\text{ cm} \) from one end (closer to knife-edge \( K_1 \)). Taking \( g = 9.8\text{ m/s}^2 \), the normal reaction \( R_1 \) at knife-edge \( K_1 \) is:
Correct answer · Option 1
\( 54.88\text{ N} \)
Explanation
Taking moments about center of gravity \( G \): \( -R_1(25) + W_1(5) + R_2(25) = 0 \implies R_1 - R_2 = 1.2g \). With translational equilibrium \( R_1 + R_2 = 10g \), solving gives \( R_1 = 5.6g = 5.6 \times 9.8 = 54.88\text{ N} \).
