Question

A metallic cube of side length $1.5m$ and of mass $3.2$ metric ton is on a horizontal rough floor. The minimum horizontal force that should be applied on the cube at a height $1.2m$ from that floor to turn the cube about its lower edge is :

• A. $1.96\times {10}^{3}N$
• B. $4.9\times {10}^{3}N$
• C. $1.96\times {10}^{4}N$
• D. $4.9\times {10}^{4}N$

Answer 1

Answer: (C)

$1.96\times {10}^{4}N$

On the verge of toppling, the normal will shift towards right most point of edge.
Torque about the edge:
$\frac{L}{2}\times 3.2\times {10}^3=F\times 1.2$
$\left(0.75\right)(3\cdot 2\times {10}^3\times 9.8)=F\times 1.2$
$F=1.96\times {10}^{4}N$