Question

If collision between the block and the incline is completely elastic, the the vertical (upward) component of the velocity of blocks at point $B$, immediately after it strikes the second incline is

• A. $\sqrt{30}m/s$
• B. $\sqrt{15}m/s$
• C. $0$
• D. $-\sqrt{15}m/s$

Answer 1

Answer: (C)

$0$

Let the velocity at point $A$ be $v$

now, $v=\sqrt{2g\left(h\right)}$

$v=\sqrt{2\left(10\right)\left(3\right)}m/s$

$v=\sqrt{60}m/s$

$vy=v\sin {30}^o\times \cos {30}^o-v\cos {30}^o\cos {60}^o$

$v_y=0$