Question

A bead starts sliding from A on a frictionless wire with initial velocity of $4m{s}^{-1}$ as shown in figure. On reaching C, its velocity will be:

• A. Zero
• B. $2m{s}^{-1}$
• C. $4m{s}^{-1}$
• D. $8m{s}^{-1}$

Answer 1

The correct option is D $8m{s}^{-1}$

Using conservation of mechanical energy:
$\frac{1}{2}m{v}_1^2+mg{h}_1=\frac{1}{2}m{v}_2^2+mg{h}_2$
i.e.
$v_2^2=v_1^2+2g(h_1-h_2)=16+2\ast 10\ast 2.4=64$
i.e.
$v_2=8m{s}^{-1}$