Question

A 10 kg block is pulled in the vertical plane along a frictionless surface in the form of an arc or a circle of radius 10m. The applied force is of 200 N as shown in the figure. If the block started from rest at A, the velocity at B would be: (g = 10 $m/s^2$)

• A. $\sqrt{3}m/s$
• B. $10\sqrt{3}m/s$
• C. $100\sqrt{3}m/s$
• D. None of these

Answer 1

The correct option is B $10\sqrt{3}m/s$

$R_{\sin 30}=\frac{d}{2}⟹R=d⟹d=10m$

Work done by force$=F.d$

$⟹W=200N\times 10m=2000J$

$d_{\sin 30}=h⟹10m\times \frac{1}{2}=h⟹h=5m$

By Work Energy theorem,

$F.d-mgh=\frac{1}{2}m(v^2-u^2)$

$⟹2000-(10\times 10\times 5)=\frac{1}{2}\times 10v^2⟹v=10\sqrt{3}m{s}^{-1}$