Centre of Mass 3 Question 22

25. The speed of the block at point $C$, immediately before it leaves the second incline is

(a) $\sqrt{120} m / s$

(b) $\sqrt{105} m / s$

(c) $\sqrt{90} m / s$

(d) $\sqrt{75} m / s$

$(2008,4 M)$

Show Answer

Answer:

Correct Answer: 25. (b)

Solution:

  1. Height fallen by the block from $B$ to $C$

$$ h _2=3 \sqrt{3} \tan 30^{\circ}=3 m $$

Let $v _3$ be the speed of block, at point $C$, just before it leaves the second incline, then :

$$ \begin{aligned} v _3 & =\sqrt{v _2^{2}+2 g h _2} \\ & =\sqrt{45+2 \times 10 \times 3} \\ & =\sqrt{105} ms^{-1} \end{aligned} $$



NCERT Chapter Video Solution

Dual Pane