Question

A bob of mass m is suspended by a massless string of length I. The horizontal velocity
v at position A is just sufficient to make it reach the point B.
The angle $\theta$ at which the speed of the bob is half of that at A, satisfies

• A. $\theta =\frac{\pi }{4}$
• B. $\frac{\pi }{4}<\theta <\frac{\pi }{2}$
• C. $\frac{\pi }{2}<\theta <\frac{3\pi }{4}$
• D. $\frac{3\pi }{4}<\theta <\pi$

Answer 1

The correct option is D $\frac{3\pi }{4}<\theta <\pi$

$v^2-u^2=2as$
$\frac{5}{2}gl-5gl=2(-g)l(1-cos\theta )$