Question

Three blocks are connected, as shown in the figure. Calculate the minimum force required to move the blocks with constant velocity. The co-efficient of friction at all surfaces is $0.25$ . [Assume that rod does not exerts force in vertical direction]

• A. $12m g / 4$
• B. $13m g / 4$
• C. $3 \, mg$
• D. None

Answer 1

Answer: (B)

$13m g / 4$

Answer 2

$F-\frac{3 m g}{4}-\frac{6 m g}{4}-T=0$ ....(i) $T-\frac{m g}{4}-\frac{3 m g}{4}=0$ ....(ii) From equarions (i) and (ii) $\Rightarrow \, F=13\frac{m g}{4}$