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 $10$. 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 $(g=10m/s^2)$.

• 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 D None of these

$F=ma$

$200=10a$

$a=\frac{200}{10}=20m/s^2$

$u=0$ (given)

Arc dist $=2\pi r\frac{\theta }{360}$

$=2\pi \left(10\right)\frac{60}{360}=10.4$

$\therefore 2as=v^2-u^2$

$\therefore 2\left(20\right)\left(10.4\right)=v^2$

$\therefore 40\left(10.4\right)=v^2$

$\therefore 416=v^2$

$v=20.3\approx 20m/s$