A 10 kg small block is pulled in the vertical plane along a frictionless surface in the form of an a

Question

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

Professor PC Thomas Classes · Answer

$W_{net} = \Delta K \implies F 	imes (	ext{chord } AB) - mgR(1-\cos 60^\circ) = \frac{1}{2}mv^2 \implies 200(2 	imes 10 \sin 30^\circ) - 10(10)(5) = \frac{1}{2}(10)v^2 \implies 200(10) - 500 = 5v^2 \implies 1500 = 5v^2 \implies v = 10\sqrt{3} 	ext{ m/s}$ (Option B)