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Three blocks A, B and C are pulled on a horizontal smooth surface by a force of 80 N as shown in the figure. The tensions T₁ and T₂ in the string are respectively

Asked in JEE Main 30th Jan 2nd Shift 2024 · Applying the second law and free-body diagrams

Figure: Applying the second law and free-body diagrams
Answer: (3) 40 N, 64 N

Step-by-step solution

Idea: each tension only has to accelerate the blocks behind it, so find the common acceleration first.

Total mass =5+3+2=10 kg, and the 80 N acts on the whole train.

a=(80)/(10)=8 m/s².

T₁ pulls A alone: T₁=5×8=40 N.

T₂ pulls A and B together: T₂=(5+3)×8=64 N.

Check the last block: 80-64=16=2×8, as it must be.

Why the other options are wrong

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