Question

The speed of the block at point B immediately after it strikes the second incline is

• A. $\sqrt{60}m/s$
• B. $\sqrt{45}m/s$
• C. $\sqrt{30}m/s$
• D. $\sqrt{15}m/s$

Answer 1

Answer: (B)

$\sqrt{45}m/s$

Along the plane velocity just before collision
$v=\sqrt{2g\left(3\right)}=\sqrt{60}m/s$
Along the plane velocity just after collision
$v_B=v\cos {30}^o=\sqrt{45}m/s$