Q.

Each of three blocks P, Q, and R shown in the figure has a mass of 3 kg. Each of the wires A and B has a cross-sectional area of 0.005 cm2 and Young’s modulus 2×1011 Nm2. Neglecting friction, the longitudinal strain on wire B is _____ ×10-4. (Take g = 10 m/s2).          [2024]


Ans.

(2)

3g=(3+3+3)aa=39g=13g

Now, 3g-T=3a

T=3(g-a)=3(g-g3)=2g=20N

Y=longitudinal stresslongitudinal strain

longitudinal strain=longitudinal stressY

=TAY=205×10-7×2×1011=2×10-4