In figure, two blocks are separated by a uniform strut attached to each block with frictionless pins. Block A weighs 400 N , block B weighs 300 N , and the strut A B weigh 200 N . If μ=0.25 under B, determine the

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Quantrex Academy · Accepted Answer

Correct answer: A. 0.4

Consider FBD of structure. In figure, two blocks are separated by a uniform strut attached to each block with frictionless pins. Block A weighs

Applying equilibrium equations,

A v+B v=200 \mathrm{ N}A_{H}=B_{H} \ldots

(ii) From FBD of block

B

,

B_{H}+F_{B} \cos 60^{{}^{\circ}}-N_{B} \sin 60^{{}^{\circ}}=0N_{B} \cos 60^{{}^{\circ}}-B_{V}-300+F_{B} \sin 60^{{}^{\circ}}=0F_{B}=0.25 N_{B}B_{H}-0.74 N_{B}=0

(iii)

-B_{V}+0.71 N_{B}=300

FBD of block

A

F_{A}-A_{H}=0N_{A}-A_{V}=400 \quad \ldotsF_{A}=\mu_{A} N_{A}\therefore \mu_{A} N_{A}-A_{H}=0 \quad \ldots

on solving the above equation

N_{A}=650 \mathrm{ N}, F_{A}=260 \mathrm{ N}, F_{A}=\mu_{A} N_{A}\therefore \mu_{A}=\frac{260}{250}=0.4

In figure, two blocks are separated by a uniform strut attached to...

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