Question

As shown in the figure a body of mass $m$ moving vertically with speed $3 \, m/s$ hits a smooth fixed inclined plane and rebounds with a velocity $v_{f}$ in the horizontal direction. If angle of incline is $30^{^\circ }$ , the velocity $v_{f}$ will be

• A. 3 m/s
• B. $\sqrt{3} \text{ m/s}$
• C. $1 / \sqrt{3} \text{ m/s}$
• D. This is not possible

Answer 1

Answer: (B)

Velocity along surface remain same
$3 \text{sin } 3 0^{\text{o}} = \text{v}_{\text{f}} \text{sin } 6 0^{\text{o}}$
$3 \times \frac{1}{2} = \text{v}_{\text{f}} \times \frac{\sqrt{3}}{2}$
$\text{v}_{\text{f}} = \sqrt{3} \text{ m/s}$