- A

- B

- ✓

- D






$ \Rightarrow {V^2}\alpha T$ (in kelvin)
not ${V^2}\alpha T$ (in ${\,^0}C$)
Hence $(B)$ is incorrect.
velocity of transverse wave in nastring
$V = \sqrt {\frac{T}{\mu }} = {V^2}\alpha T$
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Figure: $Image$
$1.$ The speed of the block at point $B$ immediately after it strikes the second incline is
$(A)$ $\sqrt{60} \mathrm{~m} / \mathrm{s}$ $(B)$ $\sqrt{45} \mathrm{~m} / \mathrm{s}$
$(C)$ $\sqrt{30} \mathrm{~m} / \mathrm{s}$ $(D)$ $\sqrt{15} \mathrm{~m} / \mathrm{s}$
$2.$ The speed of the block at point $\mathrm{C}$, immediately before it leaves the second incline is
$(A)$ $\sqrt{120} \mathrm{~m} / \mathrm{s}$ $(B)$ $\sqrt{105} \mathrm{~m} / \mathrm{s}$
$(C)$ $\sqrt{90} \mathrm{~m} / \mathrm{s}$ $(D)$ $\sqrt{75} \mathrm{~m} / \mathrm{s}$
$3.$ If collision between the block and the incline is completely elastic, then the vertical (upward) component of the velocity of the block at point $B$, immediately after it strikes the second incline is
$(A)$ $\sqrt{30} \mathrm{~m} / \mathrm{s}$ $(B)$ $\sqrt{15} \mathrm{~m} / \mathrm{s}$
$(C)$ 0 $(D)$ $-\sqrt{15} \mathrm{~m} / \mathrm{s}$
Give the answer question $1,2$ and $3.$